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).
