According to the leading proponent of assortative mating, Simon Baron-Cohen, director of Cambridge University’s Autism Research Center (and cousin to the comedian Sasha Baron-Cohen), autism tends to run in families. While that’s not news — it’s been estimated that a family with one autistic child has a 1 in 20 risk of having a second autistic child — Baron-Cohen has expanded upon that theory to posit entire communities of people with some tendency toward autism or Asperger’s syndrome, a related disorder.
http://news.yahoo.com/assortative-mating-blame-rise-autism-152400736.html
http://healthland.time.com/2011/08/19/could-the-way-we-mate-and-marry-boost-rates-of-autism/