Girls with older fathers are 6 times as likely as those with younger fathers to be the only children with autism in their families, a new study in the journal Autism reports. This effect was seen for boys and girls but was stronger for girls. The results support the hypothesis that non-inherited mutations that accumulate in a man’s sperm cells as he ages may increase the risk of autism in his children.

http://sfari.org/news-and-opinion/news/2012/effect-of-paternal-age-seen-in-girls-with-autism