Results of a study in a Swedish population have linked grandpa’s age to an increased risk of autism in grandchildren. More specifically, the study authors found that men who sired children at age 50 or older were almost twice as likely as younger fathers to have an autistic grandchild.
According to the report, published in JAMA Psychiatry (full text here), lead author Emma Frans and colleagues looked at births in Sweden beginning in 1932. Among the tens of thousands of births, the database they used had information about grandparental age for almost 6000 autism cases and for almost 31,000 controls (families with no autistic children). Grandpas who had a daughter when they were 50 or older were 1.79 times more likely to have an autistic grandchild, and if they had a son at age 50 or older, the grandfathers were 1.67 times more likely to have an autistic grandchild. It didn’t seem to matter if grandpa was on the mother’s side or the father’s side of the family.