Paternal age effect
The paternal age effect is the statistical relationship between the father's age at conception and biological effects on the child. Such effects can relate to birthweight, congenital disorders, life expectancy and psychological outcomes. A 2017 review found that while severe health effects are associated with higher paternal age, the total increase in problems caused by paternal age is low. While paternal age has increased since 1960–1970, this is not seen as a major public health concern.
The genetic quality of sperm, as well as its volume and motility, may decrease with age, leading the population geneticist James F. Crow to claim that the "greatest mutational health hazard to the human genome is fertile older males".
The paternal age effect was first proposed implicitly by physician Wilhelm Weinberg in 1912 and explicitly by psychiatrist Lionel Penrose in 1955. DNA-based research started more recently, in 1998, in the context of paternity testing.