From the abstract and the introduction:<p>&quot;<p>Diagnosed rates of autism spectrum disorders have grown tremendously over the last few decades. I find that assortative mating may have meaningfully contributed to the rise. I develop a general model of genes and assortative mating which shows that small changes in sorting could have large impacts on the extremes of genetic distributions. I apply my theory to autism, which I model as the extreme right tail of a genetic formal thinking ability distribution (systemizing). Using large sample data from the Centers for Disease Control and Prevention, I find strong support for theories that autism is connected to systemizing. My mating model shows that increases in the returns to systemizing, particularly for women, can contribute significantly to rising autism rates.  I provide evidence that mating on systemizing has actually shifted, and conclude with a rough calculation suggesting that despite the increase in autism, increased sorting on systemizing has been socially beneficial.<p>[...]<p>if you marry your high school sweetheart, you picked among those people who happened to be born in your town, but if you marry your college sweetheart, you have picked among people who chose the same college that you did. More recently, the internet has made it easier to find people with similar interests or traits<p>[...]<p>one less understood impact of assortative mating is the strong effect it has on the extremes of distributions. Positive assortative mating on a trait increases the variance of that trait, and the increase in variance causes large relative growth at the extremes of the distribution.<p>[...]<p>the growing returns to mathematical ability may have contributed significantly to the increased prevalence of autism spectrum disorders.  Diagnosed rates of autism spectrum disorders (ASDs) have grown tremendously over the last few decades, and a number of possible explanations have emerged. One of the more interesting possibilities is that ASDs are related to a genetic trait called systemizing, which governs how much our brains are wired for thinking about formal systems. High levels of systemizing may give ability in pursuits like mathematics and computer languages.<p>&quot;