The Paternal Age Effect

From Wikipedia

Paternal Age Effect
Scientists know that a woman’s age at the time she conceives can affect her offspring’s genetic make-up. Women age 35 and older are at greater risk of delivering a child with a genetic disorder, such as Down Syndrome, due to an incorrect number of chromosomes. Less well known is that a man’s age also affects his offspring. In what is called the paternal age effect, men 35 years and older have a greater probability than younger men of fathering a child with some kind of genetic defect.