Gifted Issues Discussion homepage Forums General Discussion A question of genetics

Ok this is a weird question I have been ruminating on for some time, but I have no real expertise in genetics at all. All my reading suggests that IQ is highly genetic (the potential, not the achievement). That people marry within 10 points, siblings are usually within 10 points of each other and that our friends tend to be in the ball park. That all makes sense to me.

My question is - is the incidence of high IQ children (and possibly other neurologically interesting children) increasing in recent generations because the gifted are more likely to find and marry each other now than ever before? Marrying for love is a reasonably recent phenomenon. Women working side by side with men in occupations requiring high cognitive functioning even more recent? Surely it's easier to find a partner of a similar IQ now that it was 100 years ago, let alone 500 years ago?

I wonder about those things too. My mom was proud that she not only went to college, but graduated - her friends were their for their 'M.R.S'

But I don't think arranged marriages are necessarily going to be better or worse than love matches for sorting folks along the dimension of IQ. In a way, a good matchmaker has lived in a community for a long time and 'knows her business' - why not leave such an important decision to a professional?

But our pool of possibilities with travel, college, and workplace is so much larger than when we lived in small villages. That seems like it would make some difference. On the other hand, if you live in the right small village, well there is more of a chance of genetic drift, so perhaps one would be better matched. In my grandparent's generation, lots of cousins married cousins (not first cousins) and lots of siblings married pairs of siblings from other families. When one of your siblings gets married, aren't you checking out the unattached family members on their side and mentally reviewing who is unattached on your side? I know I am.

Another possible big change in our lives that I would guess I'm seeing is that as women have more choices, fewer really bright ones become teachers. What a change I've seen in my life time! I think most of my elementary school teachers were MG, and I don't come from a fancy town.

Well, Mum - no answers, but you are certainly not alone in speculation. Sometimes when someone asks 'why' I spend so much time here, I think 'hey - any of your kids could be my child's future spouse/boss/best friend so if I help you figure out how to keep them happy and hardworking, then it comes right back to me!

Grinity

As always you make some very interesting points.

I just re-read my post and made it sound like we head off hunting for someone with a high IQ. Which obviously we don't (well most of us I assume!), at least not consciously, I just meant that it seems likely to me that these days bright men and women would be more likely to bump into other bright men and women more easily than in the past and thus more likely to find a match in a similar ball park LOG... Very interesting comment about the number of gifted women ending up as teachers. I was wondering myself how many gifted women ended up as teachers and nurses until quite recently because they were among the few acceptable careers for women.

I agree that "assortative mating" based on education has risen while that based on less-IQ-loaded factors such as religion has declined. An opposing effect leading to fewer gifted children is that IQ is negatively correlated with fertility. For example, the fertility of college educated women in the U.S. is about 1.6, below the replacement level of 2.1. The Wikipedia article "Fertility and intelligence" http://en.wikipedia.org/wiki/Fertility_and_intelligence has research on this. Worry about the dysgenic effect of a negative correlation between IQ and fertility caused me to write in another thread http://giftedissues.davidsongifted....ase_for_Having_More_Kids_.html#Post98909 , devoted to Bryan Caplan's book "Selfish Reasons to Have More Kids", that "[since] intelligence is highly heritable, it is especially important for smart people to have lots of children."

I read the Bell Curve before I was dating, and wanting smart children -- in addition to wanting intelligent company -- caused me to filter based on education and profession. I decided to have a relatively large family (three children) partly because of the social concern mentioned above. It seems to have worked -- my eldest son is highly gifted, and the second may be moderately so. I also enjoy my children.

MOT,

There's a good link at wikipedia and the references on that page.

http://en.wikipedia.org/wiki/Heritability_of_IQ

I studied medical genetics but never came across IQ of gifted kids. My theory is that the environment has changed and just like you and Grinity mentioned, women have more choices and women with high intellect attracted to smart professional men and their kids likely to gain attributes from both parents. But there are some genetic variance that gifted kid may come from poor uneducated parents as well. The likelihood of that is much lower than the kid from the high IQ parents ofcourse.

Another thing is that we are more aware (knowledgeable) of our kids than our parents and grandparents. Just like we are more aware of autism and ADHD, we are more aware of the giftedness.

It's quite funny when you said "IQ is highly genetic (the potential, not the achievement)". I was friends with the twin (brother and sister) during high school and graduate years and their scores were quite similar even though they did not study together. But the boy hang out with the wrong crowd and he ended up getting his degree 2 years after his sister and not finding as much success in his life.

I am hoping that correlation of IQ in parents and kids are not 1 or not even close.

Just the thought: high IQ people got high IQ children but they tend to have few kids so that they can nurture and pay attention to their kids. low IQ people got low IQ children but they tend to have more kids because they don't worry much. What would happen in 200-300 years?

You know I had not thought about the flip side of my question (relative fertility of IQ ranges). Probably because I came to this question through trying to figure out why my supposedly statistically rare child seems so utterly normal to me, and to my friends. She's just like their kids... Between the kids I know have tested gifted, and the kids I am certain would test gifted, its not gifted that seems abnormal in our circle. Admittedly I don't know any children personally that I know for sure are of a similar or higher LOG to DD#2, but she's not going to stand out nearly so markedly surrounded by kids within 5-10 points of her, than she would if surrounded by children 40 points different. Which lead me to wonder if there were more gifted kids now than when I was younger...

I've mulled over this question too in the past. I know in my life it certainly rings true. I wasn't able to find my "soul mate" until going to grad school. I dated other guys before then and while they were all intelligent in their own right they never had the desire/ability to discuss topics as deeply and extensively as DH can. If I would've been born years early and not have been allowed to pursue higher education my pool of guys to choose from would've been much smaller.

I find the idea that higher IQ individuals have more issues with fertility a strange conclusion. I think there are a number of reasons that higher IQ individuals have less kids:
-they use birth control more effectively
-they chose to study/pursue a career first before having kids, thus, having a smaller number of fertile years
-they realistically thought about the cost of their child's education/travel/housing and decided to limit their family size because of it
-they chose not to have a large number of kids for environmental reasons
-there seems to be a strong correlation between giftedness and being an intense child. it's hard to have a lot of intense children around!

I'm sure there are even more reasons than those lifted above. I know DH and I initially dreamed of having 4 kids but between balancing two careers and already having one very intense child (who goes to an expensive private school) we're thinking realistically that after one more we'll be done. We have a number of friends who are quite intelligent who have no desire to have kids because they'd rather focus on their careers. I do have some friends who have struggled with infertility too but in every case it was because the mother and father delayed child birth until at least their thirties (if not late thirties/early forties).

Nice list!
I might add that highest IQ parents are more perfectionistic, and vulnerable to trying 'birth-controling' styles of parenting - such as the family bed. ((wink))
I know that my natural gifted intensity kicked into overdrive with my DS, I wore him in a baby sling, nursed exclusively while working part time for 6 months - basically my perfectionism set me up to believe "There has to be a better way!" I was willing to try anything to blunt that very deep sence of lonliness I grew up with - even in the middle of a healthy loving family. When one is Intense, one doesn't need a tramatic upbringing to experience a lot of intense feelings.

And it's possible that my 'high-need' kid was successfully cue-ing me that he needed 'super-parenting' right from the begining (or that I created a monster with my liberal expectations - the world will never know)

Sometimes I dismiss my efforts as ignorant and misguided. Other times I get a sense of 'how things might have been much worse' if I hadn't gone 'over the top.'

Either way, having a 2nd child just didn't seem in the cards for us.

It seems to me that a good number of very intelligent women would choose to not have children if they have a choice - it maybe an inborn desire for most women, but not all. Barbara Walters wrote in her book that Lauren Bacall said that a woman can have 2 out of following 3: demanding job, good marriage, be a good enough mother.

I hope that isn't true, of any individual, but I can see those stressors limiting family size. I liked this book when DS was small:
Penelope Leach

I wonder if she'll do a '20th aniversary edition?'
Must send email---
Grinity

OK, putting on my demographer hat here to distinguish between fertility (the number of children a woman has in her lifetime) and fecundity (the physical ability to bear children). It's only been in the last hundred years or so that educated women had much control over the number of children that they had. Shorter life spans and infant mortality rates have also been pretty high in the past.

In a traditional farming society, the more kids the better, especially at harvest time. When a population becomes urbanized, begins working in factories or offices and living in apartments, the cost-benefit analysis begins to work against large family size.

Research suggests that the genetic component of IQ only manifests with, basically, a middle-class lifestyle, which was not attainable for the vast majority of humans for the vast majority of history.

Most people in the world, most people in this country, have little idea what their IQ might be.

Of course, I am an outlier, having grown up on a farm with a large, working-class family, and having a mentally retarded brother with whom I share two parents.

It struck me several years ago that raising children has become something like jury duty among the educated classes: one of the most important functions in our society, we leave up to the people who can't come up with a way to get out of it! It is a gross exaggeration, of course!

And, as one last note, most men in the US are looking for a women who is *almost* as intelligent as themselves, which has done quite a bit to keep this PG female out of the gene pool. Quite a bit of that endeavor, she's done on her own. Intensity played a role.

References? This seems intuitivly wrong to me, as I know many high IQ individuals who grew up in rough circumstances, and would love to learn more. I thought it was the reverse, that in Middle-class or above groups, that Enviornment didn't play much of a role in IQ (and even that I think breaks down once one starts looking at the 'over 145 crowd.) Are we saying the same thing? I'm confused Please help!
So that's why all those boys ran in the opposite direction screaming...ok maybe not.

Thanks for mentioning this one - a hot potato, but one that does need to be looked at!
Personally - I think find comfort in the 'genetic pressure to keep females away from the IQ edges - individual males are expendable, so more availible for Mother Nature to have fun messing with' idea - but not at all sure it's accurate.

I think that part of it is our cultural definition of smart is itself gender biased. I can think of any number of males who seem 'much smarter' to me than myself, but I'm way ahead of them in qualities that I see as 'expressions of social skills' rather than of 'intelligence.' In a non-gender biased world, my guess is that social skills would be seen as a deep and subtle expression of intelligence. Like Moses I can see the promised land, but I don't get to live there.

I think that 'smartness' is always going to be somewhat culturally defined idea.

Of course there is male conditioning that 'showing their smartness' is very very important, while the female conditioning runs in the other direction. I read somewhere (on the notoriously unreliable Internet I suppose) that only 30% of the males who have ever lived on planet Earth were able to reproduce. I don't see how that could actually be a fact, but it does help me be more sympathetic to Grandstanding Males when I think that it might possibly be true.

Love and More Love,
Grinity