A new study of more than 33,000 U.S. kids has found that those born to older fathers are, well, dumber. Children born to older women, however, were found to be smarter. Does this mean that the days of men thinking they have all the time in the world to have kids is over?

The research, reported in PLoS Medicine, says scientists evaluated kids at ages eight months, four years and seven years on their ability to think and reason (including concentration, memory, learning, understanding, speaking and reading). They did account for social factors that are linked to intelligence, and they consistently found that kids with older dads had lower scores than kids with younger dads, except when it came to motor skills. And the older the father, the lower the score.

Using the same data, the researchers found that older moms had more intelligent kids. Now, some might say that the older moms provide a more nurturing home environment than the older dads, as New York magazine’s Emily Nussbaum points out. Of course, we’d rather think that cougars may have the best gene pool.

Check out our slide show of Older Fathers and Their Trophy Wives.