Older grandfathers pass on autism risk through generations

Reports of autism cases per 1,000 children grew dramatically in the US from 1996 to 2007. It is unknown how much, if any, growth came from changes in autism's prevalence. (Photo credit: Wikipedia)

The study found that the risk of autism in the grandchild increased the older the age of the grandfather at the time his son or daughter was born. Men who had a daughter when they were 50 or older were 1.79 times more likely to have a grandchild with autism. Men who had a son when they were 50 or older were 1.67 times more likely to have a grandchild with autism, compared to men who had children when they were 20-24.