(NEW YORK) -- Researchers in Iceland think they've figured out why dads who postpone fatherhood to later in life are more prone to have children with problems like autism and schizophrenia.
The simple answer: older dads transmit genetic mutations to their offspring more so than their younger counterparts due to either environmental factors or cell divisions that go haywire.
Scientists at deCode Genetics Inc. in Reykjavik project that older fathers pass an average of two extra new DNA mutations with each added year of age.
One thing is fairly certain, according to the researchers: moms can't share too much of the blame for illnesses related to mental processes because they transmit about 15 new mutations to a child regardless of how old they are when becoming moms.
On the other hand, a 20-year-old male is responsible for 25 new mutations while a guy twice his age transmits 65.
Copyright 2012 ABC News Radio