A joint U.S.-British study says men aged 40 and older are far more likely to father autistic children than those younger than 30.
The study done at the Institute of Psychiatry at King's College, London, and Mount Sinai School of Medicine, New York, involved more than 100,000 children, The Times of London reported.
The findings said those born to the older fathers were six times more likely to suffer from autism and related disorders than those sired by a father younger than 30.
Abraham Reichenberg, the study's lead author, said genetic mutations in the sperm of older men may be responsible for the increased risk.
The researchers said their findings support the theory men also have a "biological clock" for producing healthy babies.
The findings, however, could not find a similar link between a mother's advancing age and autism, the report said.
The study is published in the Archives of General Psychiatry. Britain's National Autistic Society says the causes of autism are complex and require further investigation, The Times reported.
Copyright 2006 by United Press International
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