Virginity & heritability

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Genes may time loss of virginity:

As genetic determinism goes, the new findings are modest. Segal’s team found that genes explain a third of the differences in participants’ age at first intercourse – which was, on average, a little over 19 years old. By comparison, roughly 80% of variations in height across a population can be explained by genes alone.

On the other hand, conservative social mores might delay a teen’s first sexual experience, causing scientists to low-ball the effect of genes. Indeed, Segal’s team noticed a less pronounced genetic effect among twins born before 1948, compared with those who came of age in the 1960s or later.

As for the specific genes involved, another team previously found that a version of a gene encoding a receptor for the neurotransmitter dopamine is associated with age at first intercourse. Others have linked the same version of the gene – called DRD4 – to impulsive, risk-taking behaviour.

The paper is Age at first intercourse in twins reared apart: Genetic influence and life history events.

FuturePundit notes:

The team found a weaker effect from genes with people born before 1948. This supports an argument I’ve made here previously: the breakdown of old cultural constraints on behavior frees up people to follow genetically driven desires and impulses. We become more genetically driven as external constraints weaken.

When you remove the strength of environmental parameters from the equation it naturally results in a greater salience of heritable ones. Ergo, the logic whereby you can make the case that in a perfect meritocracy there will be much stronger genetic sorting by class (via assortative mating, etc.).

Related: DRD4 and virginity.

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22 Comments

  1. I’m curious about the proximate aspects of first intercourse. Why do people usually wait or ease into sex over a period of four to eight years instead of starting immediately after puberty? Is it because society and parents say this is a “bad” behavior? This would be consistent with the fact that delinquency is one of the strongest predictors of early first intercourse.  
     
    Another aspect seems to be that female anxiety, or general negative affect, is heavily intertwined with this issue. Pubescent boys who get propositioned by older female teachers seem to have fond memories of the experience, suggesting boys are psychologically ready soon after puberty. But this almost never happens for females. Females are easily traumatized (if that’s the right word) by early sexual experiences, even when those experiences are with someone they are sexually infatuated with (See also: Girl Would Be Terrified If She Knew Teacher Had Crush On Her Too). The later a female has first intercourse, the fewer negative, unresolved emotions she has about it. 
     
    I think this is consistent with the fact that early sex happens most frequently with low IQ delinquents. Males insensitive to signs of distress, either through callousness or stupidity, are more likely to pressure an encounter to their advantage. Delinquent females are more likely to fool around with thuggish males, and low IQ females are less likely to know how to negotiate a situation with a physically superior male.

  2. So can we only predict how genes interact with lower IQs? I would think that it’s easier based on the fact that it would common sense to hypothesize that the stronger/mature/loyal the parent-child bond, the greater chance for many reasons evasion of first encounter would occur. Similarly, low IQ parents beget low IQ kids so in a sense poor becomes poorer. 
     
    As an aside, what would be considered “extremely late” first intercourse for any given number or types of people (you can throw them out there)??? Is intercourse the only thing that counts, or other types of “sex”?

  3. Older women who “train” young boys are doing the younger female population a great service, IMHO.

  4. suggesting boys are psychologically ready soon after puberty. But this almost never happens for females. 
     
    Natural selection would not give us people who were physiologically ready to carry out some important function, and yet psychologically not ready to do so, however we define that. 
     
    There’s no lag between ability to digest food and being psychologically read to eat — having the thoughts, feelings, etc., that drive us to eat. 
     
    In fact, you could stand this reasoning about “psychological readiness” on its head — that boys are *not* psychologically ready for sex right after puberty, since they’ll give it away for free with no questions asked, whereas girls that age are incredibly discriminating and risk-averse (compared to when they slut it up around age 22 – 23). 
     
    Boys aren’t thinking of the consequences at all, and so feel fine, while girls are imagining just about everything that could go wrong, and so are a nervous wreck. It’s clear that girls have lower time preferences in this case, and that’s how we define “being ready” or “being responsible” in all other contexts — worrying about and looking toward the future.

  5. That inversion of the standard story is part of a much bigger picture, of course: that girls mature earlier than boys across the board.

  6. It’s true that young females in developed countries have logical reasons to worry about sex. But what puzzles me is that the anxiety doesn’t seem to primarily be about an economic calculus. At least not a conscious one. Just sort of a confused haze of anxiousness. It seems like the sort of thing that would have a biological root, and perhaps it does, but the circumstances are very different from, e.g. what the EEA would’ve featured. Age at menarche among hunter-gatherers is much later, 16-18, and if I recall correctly there isn’t a similar lag time; sex comes soon after (or even before) menarche. 
     
    Are females still going through their “psychological puberty” at 16-18 (when they typically lose their virginity), even though the modern environment has pushed their physical development as low as 10? I vaguely recall a hypothesis that body weight disorders were so common among young teen girls because they were subconsciously trying to suppress ovulation (bulimia and anorexia are associated with earlier puberty).

  7. I’ve known a couple of girls who were in love with their boyfriends and slept with them. When the girls were dumped some time afterwards, they were just devasted. One girl was 18 and spent a semester in college lying in bed and did very badly. The other girl was 17 and in high school and similarly didn’t do well in school for some time.  
     
    Their boyfriends however were just fine.  
     
    So, one thing is that you’re so vulnerable when you’re a female teenager if you’re dumped after sleeping with someone. This is probably the reason for anxiety.

  8. “I vaguely recall a hypothesis that body weight disorders were so common among young teen girls because they were subconsciously trying to suppress ovulation (bulimia and anorexia are associated with earlier puberty).” –Jason Malloy 
     
    I distinctly remember my daughter’s pediatrician telling us that my daughter’s higher than normal exercise level (ballet mostly) was likely responsible for her not yet having periods at 14. She thought she was the only girl in the world who wasn’t having one. That explanation would seem to fit with the higher age at menarche of hunter-gatherers. 
     
    But it doesn’t quite fit with the anorexia/bulimia theory, does it? Or am I confused again? I also vaguely recall that humans did not do physically well (nor did their domesticated animals) for some time after agricultural and permanent settlements appear. The physical record shows them becoming shorter and smaller. Did the age at menarche change with the diet?

  9. I know it’s not uncommon among high school girls who run cross country for their periods to stop or to become irregular. Sometimes this happens with swimmers as well. I thought I read that extremes of exercise delay menstruation or cause it to stop.

  10. But it doesn’t quite fit with the anorexia/bulimia theory, does it? Or am I confused again? 
     
    I meant that girls who have earlier puberty are more likely to develop eating disorders, not that eating disorders cause early puberty.

  11. Doesn’t the first virginity loss differs by ethnicity and culture? 
     
    — are there known human population differences in the genes responsible, like Rushton’s rule says?

  12. I’ve known a couple of girls who were in love with their boyfriends and slept with them. When the girls were dumped some time afterwards, they were just devasted. One girl was 18 and spent a semester in college lying in bed and did very badly. The other girl was 17 and in high school and similarly didn’t do well in school for some time.  
    Their boyfriends however were just fine.
     
     
    You will see this sort of behavior among older people too. Take two 30-year-olds who’ve been dating for several months. If they split up, the woman will spend the next six months sobbing in front of the TV watching Lifetime and scarfing down Ben & Jerry’s, occasionally venturing out with her girlfriends to swap stories about how all men are pr*cks. The man, meanwhile, is back out in the nightclubs within a week. 
     
    It is this gender difference in reactions to breakups that is part of the reason why sites like Match.com and eHarmony have too many men and too few women, and why singles’ bars are your proverbial sausage party. Too many women have simply taken themselves off the market to recover from breakups. It’s not the whole story, of course.

  13. I can’t speak to high-schoolers, but data from adult break-ups don’t support higher emotional recovery time for women. There is no gender difference.

  14. Speaking of dating sites and “sausage fests” (I think the use of that word alone would be a great “stay away” indicator for girl if said by a guy) ultimately it comes down to the two-Ts (the t-test if you will): timing and trust. Guys tend to look at themselves like they look at women which is just a horrible comparison; they don’t realize what is most important. Things women care most about physically are height and face, two things which you can’t do much about. ONCE you get them interested, then things like body (the things you can work on) or your joke telling ability [which is probably fixed at that time anyway] might start to help. Which brings us to the Ts. Ironically, like the period, the timing factor is crucial, because timing goes hand in hand many times with friends/meeeting places/convergent break ups. Trust as a factor is always right there. People meet at work often, right? School? They are around each other enough to trust and know what each other person is doing. 
     
    How many women going out to a nightclub even trust a “good looking” dude? I’d venture hardly many, and considering they are that whimsical the quality probably isn’t there anyway. I could go on for a long time with this but rest assured that two people with a great potential for match can be easily sabotaged by dealing with former relationships, significant others at the time, or any other multitude of things [emotions] that ruin the timing. The human animal, indeed.

  15. How many women going out to a nightclub even trust “a good looking” dude? 
     
    Women 18-27? Waaaay too many 
    Women 27+? Just about none but the most stupid

  16. Yet another reason to specialize in college girls! 
     
    All this talk makes me feel like dancing. 
     
    http://www.youtube.com/watch?v=SDgxnjgVFi4

  17. I don’t think women ever outgrow enjoying a good-looking man. Trustworthiness is hardly ever equated with looks, nor looks with IQ. In my experience, trustworthiness, brains, etc., are what you eventually marry for. 
     
    But don’t think I don’t remember fondly my dance with the brother of one of the groomsmen at my youngest daughter’s wedding. He could have been an Abercrombie & Fitch model.  
     
    Oh yeah, I had to ask him for the dance. I’m his mother’s age, but he’s old enough (and Southern enough) to have the grace to dance with me as if I were 18. (He’s also savvy enough to realize he’s actually preening for the women his age watching him. And their mothers.) 
     
    My husband had an old-man crush on one of the bridesmaids too. He’s not a dancer, but that’s one time he wished he’d learned.  
     
    The most amusing (and most applauded) cross-generational crush at that event was the 3 year old ringbearer who cut in on a guy dancing with another of the bridesmaids. 
     
    He had observed the cutting in behavior and decided he could handle that. Tugging on the pants leg of the man’s Naval Academy uniform, the little guy got their attention and got the rest of that and the next two dances with his chosen girl.  
     
    The rituals of mating begin at an early age and retain their lure as long as hip and knee joints allow.

  18. Oh, and what is a wedding reception if not a celebration of mating?

  19. Jerry Seinfeld said one of the reasons he had his first encounter of the closest kind so late (19 I think, but he may even have been older) was because he could not stand pressing the issue, so to speak, unless the girl was totally into it. Apparently he did not find himself in such a situation until he was at least 19.  
    As for girls usually remembering their first encounter of the most intimate kind in mostly negative terms–expected. Most people know this through instinct or just biological common sense, which is why even the most “liberated” parents, both fathers and mothers, get angry at the idea of anybody sexually eyeballing their teenaged daughters but not so much their sons. There’s a lot of lip service paid to the vulnerability of pubescent males being vamped by designing females, but when it actually happpens, most people aren’t too bent out of shape about it. Still, 14 year old boys fathering children by their 30 year old teachers does have a weird out factor, so I’m glad the law is there, theoretically, to intervene.

  20. Not to throw this towards another wrench in conversation but the “threatening” factor is always there with men, because of a multitude of things including: the hit and run factor, male/male competition (suitors or father/suitor), not the least of which is having a penis. It’s precisely this reason why gay men are more repulsive when thought about in comparison to others: it is the harshest +/+ when the other stress complementarity or benign/emotional (“gay” women). 
     
    Donna, no one outgrows “good-looking” anything. 
     
    What’s more interesting to me is that perhaps I am more picky (assuredly am) than most, it seems that a very good looking person can become instantly unattractive just by talking. I know this is the same for both men and women. I imagine a low-achieving male (low salary) who is 9/10 on looks would immediately be thought to be stupid … and thus instantly less attractive. 
     
    Guys have harsher standards immediately for looks. Women have what I would call thresholds, that is, does he pass the question, “Is he bare minimum if the other things are in order.” 
     
    It’s among the most interesting of analyses.

  21. How come nobody has made the “celibacy is not hereditary” quip?

  22. Oh, but it is. If your parents don’t have any children, you won’t either!

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