Older Fathers Pass On More Mutations

A recent study shows that men pass on more random mutations to their offspring than do women – about four times more, in fact. In addition, the number of mutations rises with the man’s age, approximately doubling from age 20 to age 40. In contrast, the number of mutations women pass on to their offspring is essentially unaffected by maternal age.

Actually, this makes sense. Women typically are born with all the eggs they’ll ever have, so there’s essentially no chance for the eggs to undergo genetic change throughout her life. In men, the cells that eventually lead to sperm continue to divide throughout a man’s life. As these cells divide they may accumulate mutations that are passed on.

The observation fits with a previous observation, published in April in Nature, that older men are more likely to have a mutation in a specific gene linked to autism and to father children with autism.