[R]esearchers at the Mount Sinai School of Medicine reported that a man over 40 is almost six times as likely as a man under 30 to father an autistic child. Since then, research has shown that a man's chances of fathering offspring with schizophrenia double when he hits 40 and triple at age 50. The incidence of bipolarity, epilepsy, prostate cancer and breast cancer also increases in children born to men approaching 40.
-from an article in the 6/25/2011 WSJ entitled "What's That Ticking Sound? The Male Biological Clock"