Older Fathers, Lower IQ in Kids?
Study Shows Children of Older Dads Had Lower Performance on Intelligence Tests
WebMD News Archive
Intelligence Tests for Children of Older Fathers
The older the father, the more likely the child was to score lower on the
tests, except for one measure of motor skills.
When they looked at the mother's age, however, they found that the older the
mother, the higher the children scored on the thinking skills tests. (That
finding, reported in earlier studies as well, may be due to a more nurturing
home environment if the mother is older, but this study suggests children of
older fathers don’t reap the same benefit.)
However, when the researchers adjusted for such factors as the parents'
socioeconomic status, including income and education, it modified the effect of
both parents' ages on the intelligence tests. For instance, the average score
on the Stanford Binet Intelligence Scale was nearly 6 points lower for children
born to fathers age 50 compared to those born to fathers age 20. But when the
socioeconomic factors were taken into account, the difference dropped to 2.2
While the study findings may suggest the best combination of parents is an
older woman with a younger man, McGrath says it's too early to make any
"For the moment, our study suggests that paternal age, like maternal
age, also should be 'on the radar screen'" for researchers, he says. As
research accumulates, he says, "we can put this knowledge into the public
health equation," weighing it along with many other factors before
What's behind the link between older fathers and lower IQ? "There is a
growing body of evidence suggesting that the sperm of older dads develop more
mutations, that is, spelling mistakes in the DNA code," McGrath says. His
team is researching this idea further in animal studies comparing young mice
with older ones.
Still, it's important to put the paternal age in perspective, McGrath says.
"The significance of the effect linking paternal age and child cognition is
small compared to many other socio-cultural factors -- for example good
prenatal nutrition, good nutrition for the offspring, good education, nurturing
home life, excellent teaching and school opportunities [and so on]."