But should you really forgive and move on after infidelity?

"Most of us are totally unprepared for what lies ahead in a relationship, and ignorant of what's required to last the course," Spring writes. "An affair shocks us into reality. Fortunately, it also invites us to try again."

Adds Nelson, "Many couples instinctively know that infidelity is much more complicated than our culture sometimes admits."

Couples can, and do, often find their way to an ultimately deeper, more intimate bond -- but it can take time and effort.

"In the wake of infidelity, most betrayed partners feel surprised and caught off guard," says marriage and family therapist James Walkup. "But even though the hurt person may have assumed they would not stay married to a straying spouse, they may realize they still love their partner and want to work on the relationship."

Today, not all committed relationships follow the traditional definition of monogamy. For example, both partners may decide together what constitutes cheating going forward -- whether that means flirting with a particular friend, visiting a strip club or even having sex outside the relationship.

"I have seen a growing number (of) straight and same-sex couples thrive on the infamous 'monogamish' agreement," psychotherapist Jean Malpas says. "They realize that long-term relationships might need to include the reality of attractions to other people. They carefully define trust and craft guidelines for acceptable behavior based on their level of comfort with risk and fluidity."

Such a "monogamish" approach tends to be more common among gays, lesbians, bisexuals and transgendered people, notes sex therapist Margie Nichols.

"The issue is commonly on the table for consideration or discussion when LGBTQ partners get together, and when a transgression is purely sexual (as opposed to emotional), it may be less likely to end the relationship," she says.

That's not to say that monogamish couples are safe from infidelity, however.

"Just because a couple is monogamish does not mean that they will be any more forgiving of a partner who breaks the rules and violates their trust," says social psychologist Justin Lehmiller. "Deciding whether to work things out has less to do with the gender of the partners and more to do with whether it was a good quality relationship to begin with."

Nelson adds, "Ideally, your relationship will continue to grow and change as each of you grows and changes, and it may change position on the (monogamy) continuum throughout the years."

You can't heal from infidelity overnight. Instead, take time to rebuild your relationship slowly. Rather than ignoring the affair, be willing to share your pain, listen to each other and provide comfort when one partner is remembering the betrayal -- all can help lessen the pain while re-creating the original bond that joined the two of you together.

"Turning your back on a damaged relationship may be the simplest or most sensible solution, one that frees you from the tyranny of hope," Spring writes. "But it also may be a way to escape growing up, facing bitter truths about life, love and yourself, and assuming the terrible responsibility for making your relationship work."

Some couples undoubtedly view an infidelity as the end of their relationship -- and in some cases, going your separate ways may be the best decision. But for partners who are willing to recommit themselves to each other, an affair can be a turning point.

"Sometimes my clients acknowledge that coping with infidelity was the worst and yet the best thing to happen to their relationship," Walkup says. "The distance between them has been bridged, and a deeper level of sharing and intimacy can bring joy and hope in the long run."

Arousability refers to your trait levels of SIS and SES (dual control model). Our best understanding at this point is that sexual arousability works along the lines of intelligence, height or any of the other plastic traits: you're born with a certain range of potential, and where you fall within that potential depends on life experience. It is "innate," along the lines of Jonathan Haidt's very useful definition: organized in advance of experience. That doesn't mean it's set in concrete at birth. It means that you're given a range of pontential at birth, and your experiences shape how that potential plays out.

In other words, your trait-level arousability is a result neither of nurture nor of nature, but of the interaction between the two.

Arousal, in contrast, is the product of the interaction between your arousability and the environment. And THAT is something you definitely CAN change deliberately.

Because while our capacity to respond to sexually relevant stimuli is organized in advance of experience, what qualifies as "sexually relevant" is NOT. (There may be one or two minor exceptions, but for the purposes of this question we'll cheerfully ignore them.)

Imagine a little girl, maybe 4 or 5 years old, lying in her bed at naptime, masturbating as is her habit. And imagine that her adult caregiver walks in on her and feels surprised and then embarrassed and then ashamed, and the parent says to the little girl, "Don't do that! That's bad!"

That little girl's brain creates a little glitch, a little brakes response that is associated with whatever arousal she was experiencing at the moment she was interrupted.

Now accumulate time and repetition. Let the steady drip of life corrode a pathway into the brain. The message doesn't have to be perfectly consistent - some of the learning can be contradictory, as long as the message is consistent ENOUGH, it will build a pathway in the brain deeper than the alternative pathway. And 20 years later, that girl who grew up in a culture that taught her masturbation was bad and her body was not her own to do with as she pleased, now wonders why she feels guilty when she's aroused and it takes her an hour to have an orgasm.

The good news is that this learned association can be unlearned. And that is what we can change about our sexual response.

The best book that I know of is Julia Heiman's Becoming Orgamic. It walks you through a series of exercises that help you recognize when negative thoughts or feelings emerge when you're experiencing arousal, and then help you let go of those negative thoughts or feelings when they emerge.

It takes time and patience and practice. If changing your sexual response is walking to the center of a maze, I've just described the general route. This is not the same as actually going through the maze.

If going through it alone seems daunting, a sex therapist can walk through the maze with you.

It's absolutely possible. The glitches got planted because your brain was working APPROPRIATELY. You're not broken, you just grew up in a culture that built some stuff into your brain. And now that you're a grown up, you can choose whether to keep that stuff or try something different.

It takes time. Practice. Patience. But the same processes that built in the glitches can deconstruct the glitches and build a new and different response to sexual stimuli.

At first I thought it was just the brilliant Brits.  And then I did a little research and discovered that the term is already in use in some academic and educational circles here in the U.S.  Pink Therapy is publicizing a growing cultural shift. I'm jumping for joy! I feel like I've waited a lifetime for this trend.

Because this isn't just a new alphabet soup. This is a different paradigm, a reversal of the pattern of making finer and finer distinctions of sex and gender that prevails in all areas from identity politics to scientific discourse. 

They say in scientific thinking there are 'splitters' and 'lumpers; 'different issues at different times require both approaches. LGBT activism started in the 1970's with organizations that just used 'gay' in their titles, e.g. the National Gay Task Force.  Then lesbians argued that 'lumping' them with gay men made them invisible, and that started the trend of adding letters to distinguish the different groups who wanted to be included under the 'big tent.'  Politically, this made sense.  But science followed politics, and over time researchers as well as the culture at large have behaved as though each letter in the acronym represents a distinctly different group.  And this has led to some  problems- identity politics have become conflated with reality.   This is a time for us to be 'lumping' together people who are outliers, minorities, nonconformers in their gender expression/ identity and/or their sexual expression/identity. This group of people includes those with same sex attractions, or both/pan gender attractions; it includes the whole spectrum of TGNC (transgender and gender nonconforming) people; but it also includes kinky, nonmonogamous, asexual, queer, refuse-to-label-myself people as well.

Here's why we should all switch to GSD immediately:

1. It's easy. Say it a few times - it trips off the tongue.
2. It's inclusive. We like inclusivity, right? Well, actually some of us don't, but I'm going to assume here that it's a good thing.
3. It's politically advantageous. Strength in numbers. (And yes, I know the arguments against including people who are stigmatized even more than you.  It's the reason why drag queens and other gender benders were excluded from gay politics for a long time. I disagree with the 'Virtually Normal' argument.)
4. It encourages us to find our commonalities. And believe me, as a queer shrink for 30+ years - we have SO much in common.
5. It encourages us to work together. Good karma, good communities - good politics, too.
6. THERE IS A LOT OF OVERLAP AMONG THESE COMMUNITIES ANYWAY. Especially among gay men/nonmonogamy/bisexual/kinky folk.
7. Which leads me to my last and not insignificant reason: IT IS VERY LIKELY SCIENTIFICALLY MORE CORRECT. Or at least it is a BETTER paradigm for scientific research than the one we are using now.

The paradigm that currently dominates the field of sex therapy and research is one that first and foremost is a pathology model, a medical/psychiatric model that tends to see all 'outliers' as indicators of disease. And it is a 'splitting' model: every time the psychiatric Bible, the DSM, is amended the fights are about adding new categories of sexual anomaly/pathology. This time around, in the preparation of DSM5, there was a group proposing that 'hebephilia' be added as a 'paraphilia' i.e., sexual perversion. (Hebephilia, by the way, means sexual attraction to teenagers. Perhaps a majority of men would qualify as hebephiles.)

And what I keep coming back to is - maybe our categories are just plain wrong. Different cultures at different historical periods have 'sliced up' the GSD pie in different ways. For example, although we draw a bright line between gender and sexual orientation, throughout history more commonly the two have been conflated: 'Invert' was the nineteenth century term for homosexual.

We 'see' gender and the gender to which one is attracted as the two most important dimensions of sexuality. What if there are others we are missing completely? What if there are reasons - perhaps including even biological reasons - why the kink, nonmonogamy, and LGBT communities overlap so much?  More intriguing examples:  young people are replacing 'bisexual' with 'pansexual,' and it is true that there is a huge overlap between the bisexual, kink, transgender,  and open relationship communities.  What if we are missing an important dimension of human sexuality like general openess to a multitude of sex and gender expressions? Or this - there is a growing phenomenon of previously lesbian identified transmen who become attracted to gay men after transition.  What if 'same-sex' orientation is exactly that - attraction to others of the same gender as you.

What if we don't have a clue? What if we are our understanding of sex/gender variation is in its infancy, as I believe? If there is a chance that is true - then the lens we need to use must be broad and inclusive. For now, GSD - Gender and Sexual Diversities - is the best paradigm we can use.

The survey, which asked 120,000 American adults whether they identified as lesbian, gay, bisexual or transgender, found that 6.4% of people aged 18 to 29 said they were LGBT: about three times more than people over age 65.

But do results like these indicate that younger adults are more likely to be LGBT, or are they simply more likely to acknowledge it? It's probably the latter, say my colleagues.

"These numbers might reflect a generational change in social acceptance for LGBT identities," said psychotherapist Jean Malpas, director of the Gender and Family Project at the New York-based Ackerman Institute for the Family. "Today's youth and young adults, at least in some communities, are gradually more comfortable being open about their sexual and gender identities."

Another potential reason for the increase in self-identified LGBT youth is the influence of a new generation of parents who embody a positive attitude and wouldn't have it any other way.

"Today's millennial parents are more than just accepting of their children's sexual identity. They're comfortable and embracing of it, too," said Ron Taffel, psychologist and author of the book "Childhood Unbound." "They want to actively support and engage their children through communication about all aspects of their lives."

Research, including this survey, also suggests that young women may be more likely than men to identify as bisexual.

"The pattern across surveys is that men are more likely to identify as gay, whereas women are more likely to identify as bisexual," explained social psychologist Justin Lehmiller. "We don't know exactly why this is, but many psychologists believe it results from women's sexuality being somewhat more 'flexible' or 'fluid' and men's sexuality being somewhat more 'fixed.' "

Many other young people are eschewing traditional descriptors for sexuality and gender completely.

"There's been a lot of work done on how LGBT youth is more and more frequently rejecting labels altogether, blurring the lines between sexual orientation and gender, creating new labels and identifying as gender-queer, gender-fluid or pansexual, to name a few," said sex therapist Margie Nichols. "The very term 'LGBT' is too confining now, which is why I prefer the term Gender and Sexual Diversity, or GSD."

That term could also include the 1% of people who identify as asexual, which means they aren't sexually attracted to anyone.

"While we're creating space for a variety of sexual identities, we also need to create space for non-sexual identities," said college sex educator Emily Nagoski.

Indeed, many of the experts I spoke to expressed frustration that Gallup and other surveys limit the options from which a respondent can choose.

"The terms lesbian, gay and bisexual just don't capture all sexual minority identities," Lehmiller said.

Nichols agrees. "These studies are missing a tremendous opportunity by not including an 'other' category. It's a shame, because the 'other' category is the wave of the future."

Separate from sexual identity is gender identity. While not addressed in the Gallup survey, experts say, this distinction is increasingly important, particularly for today's youth.

"Gender nonconforming expression and identity are different from sexual orientation," Malpas explained.

"Sexual orientation is about who you are attracted to and who you fall in love with. Gender expression and identity refer to the gender you feel comfortable expressing and identifying with, which might or might not be aligned with the biological sex you were assigned at birth."

As transgender and gender-nonconforming children and teens become more visible, both in communities and in the media, parents are less likely to dismiss them.

"Only a decade ago, a parent would have probably answered 'stop saying silly things' to a 6-year-old son who insisted on being a girl," Malpas added. "Today, the same parent will stop and think about the transgender children they've seen on TV or in magazines and may more readily inquire with professionals and other parents."

More than just stop and think, they'll also hopefully want to talk. Says Taffel, who specializes in breaking through to teens, "Open communication is a primary value for today's parents, much more so than setting limits and rules, and the spirit of open communication trumps the content of any conversation."

While it's important not to confuse gender and sexual identity, parents can take a similar approach in discussing them with their kids.

"Of course, you should reassure the child of your love, but you'll also want to find ways to expose your child to others like him or her so the child doesn't feel different or alone," Nichols suggested. "Allow yourself to experience mixed or negative feelings if you have them, and consider joining a support group. You've also got to be prepared to be your child's advocate with schools, neighbors and community activities."

I find the survey results very encouraging, as they indicate not just a shift of differences in human sexuality toward the mainstream but also suggest that the future is promising for people who don't fit into "the norm."

"We're evolving, culturally, beyond the need to impose rules on who's allowed to do what with their genitals and their hearts," Nagoski said. "This new generation of young people understands that love is love, that people are people and that the freedom to experience joy and mutually consensual pleasure is a birthright."

Believe it or not, you aren't the first guy who has fantasized about this. In fact, a similar scenario has even appeared on one of the Top 10 Lists of Sexual Fantasies that I have compiled on my website. So let's talk first about where this fantasy might come from; however, please keep in mind that different reasons might exist for different men.

Perhaps the most common reason I hear from non-psychologists in trying to explain this fantasy is something along the lines of "well, duh, he's either gay or bisexual." This may be true for some guys, particularly guys who are interested not just in watching, but also joining the action--however, I don't think this explains why so many men have this fantasy. Instead, there may be some psychological and/or evolutionary reasons behind it.

For instance, some men may find it arousing to see their partner sleep around simply because they are voyeurs. In other words, they may derive great pleasure from watching other people engaged in sexual activity. A certain degree of voyeurism is common, given the widespread popularity of pornography; however, some people have more intense degrees of voyeurism than others and are only satisfied seeing the real thing in person.

Another possibility is that there is a biological or evolved mechanism that stimulates arousal in this situation. Specifically, seeing another man (or multiple men) bedding a desirable woman may stimulate sperm competition. The basic idea is that when such a situation is observed, men's bodies and brains respond in such a way as to increase the likelihood that their sperm will outcompete that of other men. Consistent with this idea, both men and women report that after a period of separation or when female infidelity is suspected, the male partner thrusts faster and deeper during their next sexual encounter, possibly as a means of displacing other men's semen.¹ Perhaps even more compelling, research has found that after viewing pornography that depicts sperm competition (i.e., two men having sex with the same woman), male participants exhibited a greater percentage of active sperm in their ejaculate than did men who viewed porn featuring only women.² Thus, it may be adaptive for men to be aroused by this situation because it will increase the odds that they will impregnate their partner instead of someone else.

Of course, other explanations are also possible (e.g., some guys may just have a desire to see their partner completely satisfied, while others may enjoy the fact that it is a forbidden or taboo activity). But no matter the reason, as long as the activity is consensual and nobody feels pressured into doing something they do not want to do, acting on this fantasy could potentially enhance sexual satisfaction for everyone involved.

As for the question of "how to talk your wife into it," I cannot tell you that because I do not know how your wife feels about nonmonogamy and the prospect of sleeping with other men. Like any other sexual fantasy, this is not something you can force upon your partner--going through with it has to be a mutual decision. The only thing you can do is tell your partner about your fantasy and see where it goes. Of course, that's easier said than done because sharing fantasies can be difficult, especially when they involve bringing other people into the mix. This is the kind of thing where you don't just want to blurt out what you're thinking; rather, you want to work up to it slowly through a more general process of communicating about your desires. Thus, the timing is important, as is the way it is framed because your partner may interpret this fantasy in a lot of different ways.

¹Gallup, G. G., Burch, R. L., Zappieri, M. L., Parvez, R. A., Stockwell, M. L., & Davis, J. A. (2003). The human penis as a semen displacement device. Evolution and Human Behavior, 24, 277-289.

²Kilgallon, S. J., & Simmons, L. W. (2005). Image content influences men's semen quality. Biology Letters, 1, 253-255.

In fact, two recent studies show that cell phones can have a negative impact on close relationships.

Researchers from the University of Essex found that people who engaged in personal discussions when a cell phone was nearby -- even if neither was actually using it -- reported lower relationship quality and less trust for their partner. They also felt their partner was less empathetic to their concerns.

Other studies suggest that cell phones can distract our attention from the present moment. And that's a problem, considering the results of the Mobile Mindset Study, a recent survey that found three out of five U.S. smartphone users don't go more than hour without checking their gadgets.

Taken a few steps further, smartphones, tablets, and laptops -- and the social media they often support -- have the potential to tear couples apart.

I've talked before in this column about the capability of Facebook and other social media to threaten relationships: They provide a sense of instant gratification that stimulates our brain's reward centers, offering quick hits of novelty that can be downright addictive.

Plus, they allow us to connect with friends, co-workers, and even former flames, fostering an immediate and intense sense of intimacy that can lead us to romanticize these connections. At best, you're giving your energy to these digital distractions, not your partner. At worst, you could be setting the stage for emotional infidelity.

Of course, it's unrealistic to ditch your smartphone altogether, especially if you also need it for work. But there are things you can do to use it wisely -- and even help improve your relationship. Here are three tips for making technology work for you and your partner:

Set it aside. It should go without saying that cell phones are best kept out of sight and out of mind when you're on a date. Turn it off and place it in your bag or pocket for the duration -- the world won't end if you can't check your e-mail for an hour or two.

I also recommend shutting down phones, tablets and laptops at night, or at least charging them in a room other than your bedroom. Not only can they interfere with your ability to relax and unwind, but their distracting presence can also put a real crimp in intimacy.

Rethink social media. We've talked about the possible perils of connecting with your exes online. But I typically advise that you don't "friend" your partner, either. As Facebook friends, you have access to the most mundane parts of your significant other's day, from what he ate for lunch, to what new movies she wants to see. Talk about removing any sense of mystery!

If you do want to connect online as well as off, consider joining a digital service that helps foster togetherness. Best described as intimate online spaces for just you and your partner, programs like Between or TwoCup offer a place to share private memories, messages, and photos -- away from the prying eyes of others.

Make a sexy connection. Technology isn't all bad: It can actually bring you closer together -- and even add some spice to foreplay.

Use your smartphone to send your partner a sexy e-mail, voicemail message, or "sext" describing a fantasy or your plans with him or her for the evening. Engage in a little Skype or FaceTime flirtation, especially if one of you is out of town. Just a word of caution: Be sure to use personal, not company accounts.

Smartphones and other gadgets can clearly have a negative impact on your relationship -- but they don't have to. By learning to use them wisely, you can start to feel more connected to your partner than ever.

After puberty, testosterone levels are usually at their highest, driving competitiveness, aggression, and sexuality.  It seems that almost anything from nervousness, to excitation, to daydreaming, to boredom can trigger an erection.  For many teenage guys, masturbating daily or even several times a day is common without untoward consequences.

Then we cut to a sexual situation.  Maybe there is the expectation of having sex with a partner that is very attractive and exciting, so much so that a guy becomes anxious about his ability to please his partner.  If his anxiety starts to overshadow his excitement, he may not be able to keep an erection or even get one at all.  Once the anxiety becomes the predominating thought, not only does it flood the system with adrenaline, but it leaves little room for real erotic thoughts that drive arousal.

What kind of response a guy gets to his level of arousal can also greatly influence the level of his erection or ability to maintain it.  A strong, judgmental, hysterical, or demanding attitude on the part of his partner is not only insensitive, but works directly against his arousal and can make the situation even worse.  The more that a guy can continue to focus primarily on what he finds exciting without getting pressure from his partner or from his own performance anxiety, the better the chance that he will have in getting an erection that he is pleased with and keeping that erection.

When anxiety takes hold, the best tactic is to redirect one's thoughts to whatever activity or stimulus is pleasurable and erotic in the moment.  Don't worry about what will happen 5 minutes from now since you are only in control of the present.  Similarly, don't continue to beat yourself up about past disappointments, because those moments have passed and you have the ability to shape each moment differently.  Instead, pick the first thing that is the most erotic for you and let yourself completely focus on this.  Sex is much better when it is a "want to" and not a "have to."

One of the earlier explanations, known as genital echo theory, proposes that female breasts only became a significant factor in attraction once human beings started walking upright.¹ Before we started walking on two legs, the biggest source of visual excitement for men was the female buttocks. However, when we stood up, the buttocks was no longer as prominently displayed. As a result, the thought is that the breasts became bigger and more pendulous in order to mimic the visual appeal of the buttocks (think about it this way: cleavage bears a striking resemblence to the rear end, doesn't it?).

One of the newer theories is that men have evolved a preference for breasts because stimulating them enhances bonding with a female partner.² The basic idea is that women find breast and nipple stimulation to be sexually pleasurable. In fact, some women find nipple stimulation so pleasurable that it can lead to orgasm in and of itself! In addition, such stimulation causes the release of oxytocin in the brain. Oxytocin is a hormone that facilitates bonding between humans. Research has shown that it plays a role in the bonding that occurs between mother and child during breastfeeding, as well as between romantic partners who have sexual contact. Some scientists believe that men have developed an attraction to breasts precisely because breast and nipple stimulation tap into this neurochemical bonding system that can bring couples closer.

Other theories certainly exist (e.g., breasts may also be desired because they indicate sexual maturity and fertility status), however none of them tell us definitively why heterosexual men tend to look at women's breasts like they are one of the seven wonders of the world. These theories are complicated by the fact that not all men are into breasts, and that there are big cross-cultural variations in terms of what men find attractive about the female body. Although scientists do not fully agree on a single explanation, there does seem to consensus that men's fascination with breasts has evolutionary roots.

Check more of Dr. Lehmiller's articles on his blog, The Psychology of Sex.

¹Fisher, H. E. (1992). Anatomy of love. New York: Fawcett Columbine.

²Young, L., & Alexander, B. (2012). The chemistry between us: Love, sex, and the science of attraction. New York: Penguin.

I'm always careful to make clear that while the adventures of Ana and Christian may make for a compelling erotic yarn, their story is by no means an accurate depiction of BDSM relationships (bondage, discipline, dominance, submission, sadism, masochism), nor is "Fifty Shades" any sort of guide book.

For instruction on that topic, you'll need to turn to the works of true sex-positive educators such as Clarisse Thorn or Tristan Taormino and their books "The S&M Feminist" and "The Ultimate Guide to Kink," respectively.

But there's no denying that "Fifty Shades" has sparked widespread interest in how to improve our sex lives -- and what better way to do that than via a good "how-to" book?

If you're uncomfortable talking about sex to your friends, doctor, therapist or even your partner, such books can be an important resource, whether they impart new information, help you work through an issue, inspire you to become more adventurous or simply turn you on.

So, in the spirit of sharing, I asked some of my favorite sex experts to pick their favorite sex books:

Debby Herbenick, a research scientist at Indiana University and the author of "Sex Made Easy:"

"Hands down, I recommend 'The New Male Sexuality' by Bernie Zilbergeld. A classic in the field, it gives a rich picture of men's sexual lives including myths they're taught about sex and common problems such as erectile issues, communication blocks and rapid ejaculation as well as solutions for these problems."

Joe Kort, a clinical sexologist and founder of the Center for Relationship and Sexual Health:

"I recommend Jack Morin's 'The Erotic Mind,' which helps remove the shame of sexual behaviors and fantasies by understanding what they mean in a nonsexual way. Morin addresses where fantasies and desires come from and how shame can be removed and replaced with healthy acceptance for individuals and couples."

Amy Levine, sex coach and founder of Ignite Your Pleasure:

" 'Hot Sex: Over 200 Things You Can Try Tonight' by Jamye Waxman and Emily Morse is a fun, sensual, seductive, creative and tantalizing book filled with more than 200 ways to tease, play, entwine and explore. When I coach couples who are in a sex rut, I suggest they use this book as a tool."

Laura Berman, sex educator, researcher and therapist:

"If I had to pick, I would choose either 'The Anatomy of Love' by Helen Fisher or 'The 5 Love Languages' by Gary Chapman. Both are extremely helpful for couples to understand how men and women are wired differently and to learn how to love one another in a way that lasts."

Justin Lehmiller, Harvard University social psychologist and online sex columnist at The Psychology of Human Sexuality:

" 'The Technology of Orgasm' by Rachel Maines chronicles the history of 'hysteria,' a bogus female medical condition that led to invention of the vibrator. Maines' book is a meticulously researched, fascinating and humorous look at the origin of hysteria and the birth of the motorized sex toy.

"I also adore 'Bonk: The Curious Coupling of Science and Sex' by Mary Roach, which traces the history of how scientists have studied sexual arousal and orgasm in a very engaging way that refuses to take itself too seriously and never gets bogged down in jargon or technicalities.

"On a personal level, 'Bonk' holds a special place in my heart for helping me realize how much fun a career in sex research could be."

Megan Andelloux, certified sexuality educator and sexologist:

" 'America's War on Sex' by Marty Klein describes ridiculous sex laws and research that Americans are led to believe are true. It's a must-read book for anyone interested in sociology, psychology, sexuality education, law and parenting.

"I'm also a fan of 'My Secret Garden' by Nancy Friday, which discussed women's fantasies well before erotica became truly popular."

I've read and recommend many of these books myself, and this list is only the beginning of many exceptional works worth exploring and learning from.

In my opinion, no list would be complete without Esther Perel's "Mating in Captivity," an excellent guide to integrating a sense of sexual mystery into long-term relationships.

And on a personal note, in 10 years of writing sex books, my first, "She Comes First: The Thinking Man's Guide to Pleasuring a Woman," remains my most popular.

At the time, I often mused that many men -- through no fault of their own -- knew more about what was under the hood of a car than under a woman's clothes or what was behind her orgasm.

In writing "She Comes First," I am grateful to the Federation of Feminist Women's Health Centers and their book, "A New View of a Woman's Body" (unfortunately now out of print) and to Rebecca Chalker's excellent book, "The Clitoral Truth." Any man or woman truly interested in deepening their knowledge of a woman's full sexual potential should give this book a read.

No matter where your sexual interests lie, you're sure to find something new on the shelves of your local bookstore. And if you're too embarrassed to shop in person -- well, that's the beauty of the Kindle, Nook and other e-readers -- no plain brown wrapper necessary!

Any books to add to the list that have helped you improve your sex life? Tell me about them in the comments below. I'm always looking for a good read.

When it comes to teaching kids about sex, most parents simply don't know what they should say, how they should say it, or when these conversations should begin. This seems to be especially true for dads, with research finding that fathers are typically far less involved than mothers in their children's sex education.¹ Although there may be any number of reasons for this (e.g., women are more likely to be primary caregivers and are usually seen as the health educators in the home), the fact of the matter is that dads sit on the sidelines far too often in this regard. And when dads do talk to their sons about sex, these "talks" usually involve jokes, awkward silence, and a tendency to keep the more serious issues at a distance.² This is a shame because by a wide margin teenage boys report that their parents are the most influential figures in their lives when it comes to making decisions about sex.³ And a lack of open and honest sexual communication has negative consequences. For instance, most teens report that they would have an easier time postponing sexual activity if they could talk more to their parents about sex.

So, for all of the dads out there, when should you have "the talk" with your son and what should you say? Below are a couple of tips to help get you started on the right foot.

1. Initiate the talk about sex early - ideally by age 10 or 11, if not sooner. Far too many parents want to wait until their kids are older or until the time seems "right" to broach the subject. However, the longer you wait, the less likely it is that the talk will ever happen, or if it does, it may be too little, too late. Admittedly, it is more difficult with boys than it is with girls to determine the "right" age, because with girls menstruation provides a natural segue into talking about sexual development. However, consider the fact that most boys are searching for pornography by the age of 10 or 11. With that social marker in mind, it tells us that boys need a relatively early lesson so that parents do not miss out on a vital opportunity to shape their sons' ideas about sex and relationships.

2. Find out when and what your kids are learning about sex in school - and be prepared to fill in the gaps. If possible, consider attending the sex education program your kids will be exposed to or, at the very least, speak with your son's teacher about what exactly will be covered. The idea here is that you do not simply want to assume that your kids are getting all of the knowledge they need elsewhere. For example, just consider that more than one-third of teenage boys report receiving no formal instruction regarding contraceptive use in school.⁴ You need to know what the school is providing so that you can supplement the information and also be prepared to answer any questions that your child might have.

4. Don't leave all of the hot-button and serious issues off of the table. As I mentioned above, dads have a tendency to keep the more serious issues at bay, but please try to avoid doing this. The talk that you have about sex should include more than just the mechanics of how babies are made, because human sexuality is far more complex and your kid wants (and needs) to know more than just the basics. Topics such as sexual orientation, masturbation, oral sex, and sexual assault should all be addressed too. You might think that teaching your son how to avoid getting a girl pregnant is the only goal here, but keep in mind that vaginal intercourse is just one of many sexual activities boys might pursue and that not all boys are heterosexual. How do you feel about other activities and what should your son know to keep himself (and his partners) safe?

5. Keep the conversation going and be sure to talk about relationships too. Finally, keep in mind that "the talk" isn't just a one-time thing. This is an ongoing conversation you will need to have with your son as he gets older because new questions are bound to come up for him and it's impossible to teach someone everything they should know about sex and sexuality in the span of just one short conversation. Also, keep in mind that your talks should not focus exclusively on sex--it is important to talk about relationships too. Developing healthy relationships is something that most of us learn by trial and error because it is not taught in elementary or high school, and not necessarily even in college. Sex, love, and intimacy all go together, so try as much as you can to relate these to one another over the course of your talks.

On a side note, while the focus of this article was on dads talking to their sons (a common problem area), most of the above tips would be useful for any parent who is trying to figure out how to talk to their child about sex. For more resources on this topic, check out Talking With Kids About Sex.

Check more of Dr. Lehmiller's articles on his blog, The Psychology of Sex.

¹Walker, J. L. (2001). A qualitative study of parents' experiences of providing sex education for their children: The implications for health education. Health Education Journal, 60, 132-146.

²Wight, D. (1994). Boys' thoughts and talk about sex in a working class locality of Glasgow. Sociological Review, 42, 703-737.

³Albert, B. (2010). With one voice 2010: America's adults and teens sound off about teen pregnancy. The National Campaign to Prevent Teen and Unplanned Pregnancy.

⁴Martinez, G., Abma, J., & Copen, C. (2010). Educating teenagers about sex in the United States. NCHS Data Brief. Retrieved from: http://www.cdc.gov/nchs/data/databriefs/db44.pdf

⁵Walker, J. (2004). Parents and sex education--looking beyond 'the birds and the bees.' Sex Education: Sexuality, Society and Learning, 4, 239-254.

In a recent study published in the Asian Journal of Andrology, researchers measured the length of men's fingers and penises while they were under anesthesia for an operation.¹ And yes, the researchers did obtain the men's consent first, so you don't need to worry that you might be an unknowing participant in a penis size study the next time you find yourself in an operating room. Different people recorded the penile and finger measurements to ensure that knowledge of one size did not influence measurement of the other. On a side note, I should mention that two different penis measurements were taken for each patient: flaccid and stretched. The reason for this is because flaccid length is not necessarily a good indicator of erect length. The stretched measurement was thus meant to approximate size during sexual arousal.

Results indicated that men with lower finger length ratios had longer stretched penises. What this means is that the shorter a man's index finger is relative to his ring finger, the larger his erect penis is likely to be. This same finger length ratio did not predict flaccid penis size--the only factor that predicted that was height. Thus, taller men tended to have longer flaccid penises. However, height was not related to stretched penis size in this study.

How do we explain the finger length finding? The researchers believe it is a result of prenatal testosterone exposure. Generally speaking, testosterone exposure in utero is linked to having an index finger that is shorter than the ring finger--in fact, men typically show at least some finger length difference of this nature, whereas women usually do not (except for lesbians). We know that testosterone exposure is linked to penile size as well. Thus, it may be that early exposure to high levels of testosterone exaggerates both finger length ratios and penis size.

On a side note, this finding fits well with previous research on sexual orientation and the theory that homosexuality is a product of higher than usual levels of testosterone exposure in the womb. Studies have found that gay men tend to (1) have even lower finger length ratios than heterosexual men² and (2) typically report larger penises on average (specifically, about one-third of an inch larger).³ With all of this converging evidence, it suggests that there might really be something to this idea. As always, however, keep in mind that almost no findings are universal and there are always exceptions to the rule. In other words, don't judge a man solely by the size of his hands.

Check more of Dr. Lehmiller's articles on his blog, The Psychology of Sex.

¹Choi, I. H., Kim, K. H., Jung, H., Yoon, S. J., Kim, S. W., & Kim, T. B. (2011). Second to fourth digit ratio: A predictor of adult penile length. Asian Journal of Andrology, 13, 710-714.

²Blanchard, R. (1997). Birth order and sibling sex ratio in homosexual versus heterosexual males and females. Annual Review of Sex Research, 8, 27-67.

³Bogaert, A. F., & Hershberger, S. (1999). The relation between sexual orientation and penis size. Archives of Sexual Behavior, 28, 213-221.

For starters, keep in mind that this research is correlational in nature, which means that we cannot make any assumptions about cause and effect. Thus, even though there is a statistical association between timing of sex and relationship outcomes, it doesn't mean that those outcomes were caused by how long people waited to have sex. It could just be that people who have sex sooner are different in some way (e.g., in terms of personality) and perhaps those differences are responsible for producing the observed association. Thus, saying that timing of sex "causes" harm or negatively "impacts" relationships is just plain wrong and irresponsible because we cannot conclude that based upon these data.

Second, every single media report has ignored the fact that average levels of satisfaction, communication, and commitment were high for both men and women no matter when they started having sex. For instance, let's look at relationship satisfaction, which was rated on a scale ranging from 0 to 12 in this study. The midpoint for this scale is 6, which means that anything above that represents satisfaction and anything below that represents dissatisfaction. For women, those who had sex in the first month had a satisfaction score of 7.9, while those who waited six or more months had a score of 8.5. For men, the numbers were 8.2 and 8.5, respectively. Thus, average levels of satisfaction were high for all groups, so where is the "harm" and all of the "unhappy" couples? In my view, what we're dealing with here is a question of statistical significance versus practical significance. What I mean by this is that while the scores may be statistically different between groups, is that one-half point difference in relationship satisfaction all that meaningful in real life? That's debatable. Perhaps if the researchers showed that early sex was linked to a higher likelihood of divorce, we could make a case for relationship "harm." But if everyone is reasonably satisfied and committed and the differences are small between groups, it seems disingenuous to claim that early sex is really hurting people's relationships.

Last but not least, this study found that the association between early sex and relationship quality was largely accounted for by whether couples lived together prior to marriage. Let me explain: people who had sex sooner were more likely to cohabitate prior to getting married. Once the researchers took this factor into account, the association between early sex and relationship quality disappeared. Why is that? We know from a variety of studies that cohabitation is linked to having more marital difficulties.² We don't know exactly why--it just is. But given that cohabitation seemed to be responsible for the association found in this research, it would appear safe to conclude that this study tells us more about the potential effects of cohabitation on relationship quality than it does about timing of sex.

So will jumping into bed sooner truly hurt your chances at a lifetime of happiness? There's nothing in this study to make me believe that's the case, so don't be swayed by the sensationalized headlines that suggest otherwise.

Check more of Dr. Lehmiller's articles on his blog, The Psychology of Sex.

¹Sassler, S., Addo, F. R., & Lichter, D. T. (2012). The tempo of sexual activity and later relationship quality. Journal of Marriage and Family, 74, 708-725.

²Jose, A., Daniel O'Leary, K. K., & Moyer, A. (2010). Does premarital cohabitation predict subsequent marital stability and marital quality? A meta-analysis. Journal of Marriage and Family, 72, 105-116.

It's not surprising why sleep trumps sex: Between work, family and social obligations, our need for shuteye often suffers.

Add in problems such as financial stress, health issues and relationship woes, and you can see why sex tends to drop to the bottom of our "to do" list -- if it's on there at all.

And when we do finally hit the sheets, many of us are more apt to hold onto our smart phone, tablet or other gadget than our partner's hand.

"Many of us are multitasking throughout the day for extended periods of time -- constant stimulation that can allow for enriching experiences," says Amy Levine, sex coach and founder of Ignite Your Pleasure. "However, that can also take its toll on our sex lives."

In some cases, though, simple exhaustion isn't the only reason why sex takes a backseat to sleep.

Unless you've been diagnosed with a health condition that saps energy, such as chronic fatigue syndrome, it's possible that factors other than a busy lifestyle are at play.

"Boredom could be to blame," Levine says. "If you think or feel sex is going to be status quo, it will feel like a chore rather than something that's satisfying."

Also likely: a low sex drive. According to a 2008 study published in the Archives of Internal Medicine, between one-third and one-half of all women will find themselves coping with low sexual desire at some point in their lives. And while we're lacking such strong statistics for men, I and many other experts believe that low libido is increasingly becoming a problem for guys, too.

Although any number of factors could be to blame for these dips in desire, many of the same triggers that make us exhausted -- like stress, anxiety, worry -- are also linked to decreased desire in both men and women. Some people may confuse a low libido with being too tired for sex; for others, exhaustion itself seems to trigger a lower sex drive.

"A lot of women are satisfied with their relationships and enjoy sex once it's under way but are just too tired and stressed to feel sexual desire," explains Laurie Mintz, a University of Florida professor of psychology and the author of "A Tired Woman's Guide to Passionate Sex."

The book was shown in a published study of 45 women to significantly increase sexual desire, arousal, satisfaction and overall sexual functioning in those who followed the book's program.

Fortunately, there's much you can do to create both the time and energy to make sex a regular part of your routine again. Try these steps to get back on track:

Get on a regular sleep schedule

It's the end of a long day, the kids are finally in bed, and all you and your partner want to do is -- well, veg out in front of the TV, or putter around on the Internet, or play a few rounds of Words with Friends.

Says Patty Brisben, educator and founder of PureRomance.com, "The average American spends 2.7 hours a day watching TV, according to the American Time Use Survey. So you have to ask yourself which is more important to you: your relationship or American Idol?"

Try to stick to a regular bedtime, and devote the last hour or so of your waking time to your partner. Even if you do nothing more than cuddle, you're setting a schedule that allows time for more when you're ready. Eventually, your mood will follow.

Think outside the box

It's easy to say, "Let's have sex tonight," early in the day when your energy is still high. Yet most of us wait until nighttime to get intimate, and by then we're often too tired to make a move.

"Some people are more aroused during the day than at night," Levine says. "Make your arousal pattern work with your schedule and that of your partner so you can enjoy physical intimacy." That might mean indulging in morning sex before work or a lunchtime quickie -- whatever works for you.

Make a date

Think scheduled sex is boring? Not necessarily. There's a common assumption that spontaneous sex is best, but "planned encounters help build anticipation and relieve tension within your relationship," Mintz says.

Get a sitter and head out for date night, play hooky from work, or make time for sex when the kids are at a friend's house, for example.

Adds Brisben, "Scheduling sex is great for someone who loves to make a 'to-do' list. You know you're not going to sleep until that box is checked off. Plus, it'll establish a pattern of healthy sexual behavior. They say it takes 21 days to form a habit. Once that habit is formed, you won't want to go to sleep unless you've had sex."

Just do it

It can be tough to feel aroused when all you want to do it sleep. But stick with it.

Like other forms of exercise, "sex can give you an energetic buzz," Levine says. "You just have to be willing to push past the feeling of tiredness to experience the pleasure that will ultimately recharge you.

"If you shift your schedule so you get enough sleep and reprioritize your day to the essentials," Levine says, "being tired doesn't have to be a factor that influences your sex life."

And remember, sex begets sex. Once you get back into the swing of things, you're likely to start wanting to get -- and stay -- intimate more often. When you wake up and smell the coffee, it will smell all the better for having had sex the night before.

I've just described a typical "party plan," a marketing technique that melds a social event with direct product sales. Party plans are nothing new - Tupperware, Pampered Chef and Mary Kay have been around for decades.

What makes this scenario different is that the consultant isn't hawking egg slicers or lipstick. Instead, she's sharing the buzz on the latest vibrators, lubricants and other bedroom accessories.

It's a creative, blush-free way to bring these products to women who may be squeamish or shy. But are the attendees walking away with more than just a bag of sex toys?

Sex toy parties have been around since the 1970s, although they didn't truly begin to gain popularity until the '80s and '90s. These days, such get-togethers have gone mainstream, and most women I know have attended at least one, often at bachelorette parties.

It's estimated that there are tens of thousands of consultants in this country, working for Pure Romance, Passion Parties, Intimate Expressions or one of the many other franchises.

As with other party plans, consultants give product presentations, with the host typically receiving merchandise or a discount in return. But that may be where the similarities between sex toy parties and, say, Tupperware parties end.

Sex toy parties go beyond simple commercialism and can teach women about their sexuality, according to Patty Brisben, founder of Pure Romance.

"We are not about the sale of a product - we are about the education behind it," she says. "Our mission is to provide a very safe environment for women to learn about and discuss sex and sexuality. The bottom line is that people will not use their products if they don't know how to use them or are intimidated."

In fact, party-goers may rely on consultants to expand their knowledge about sexuality in general: A 2009 study by researcher Debby Herbenick and others at Indiana University's Center for Sexual Health Promotion found that sex toy party consultants are often asked for accurate sex advice and may even have backgrounds in health or sexual education.

Similar research by the same authors, published in the November 2009 issue of Sexual Health, suggests that such parties allow women to learn more about specific topics, including increasing desire/arousal, orgasm, erection and ejaculation, and vaginal dryness and lubrication.

"Female in-home sex toy party facilitators have the potential to provide a diverse group of women with opportunities to access sexuality information, products, and communication," they write.

While other party plans might involve testing out a recipe or demonstrating a makeover, sex toy parties tend to have greater goals. Passion Parties, for example, are primarily geared to women in couples; their mission involves fostering "passionate monogamy." Surprise Parties seeks to help women achieve sexual fulfillment. And Pure Romance focuses on female empowerment.

"Sex toy parties should be a platform for women who want to be responsible for their own sexuality," says Brisben. "We are the place for women to start getting a better understanding of their needs, their wants, and their desires. And when you understand the mechanics of what makes you feel good and why, it allows you to know what to ask for."

Whether you're easily embarrassed or totally comfortable talking about your sex life, sex toy parties can be a great opportunity to chat with your girlfriends, learn something new, and become a little - or a lot - more in tune with your sexuality.

Who knows - you might even leave with a few new treats. Above all, have fun. Isn't that what parties are all about?