Learn about the genetic biological clock and teach everyone you know, it has been kept under the radar

Men manufacture new sperm continuously throughout life, with each one living about 74 days. Scientists once thought that defective sperm were doomed to die with the roughly 40 million unrequited suitors in every ejaculation. But now it seems that some kinds of damage do not hinder sperm in their race to fertilization. The result can be embryos with high vulnerability to problems including autism and cancer.

Men's reproductive health is most robust in their twenties, and after that it's downhill. Each year after puberty, a man's spermmaking cells divide about 23 times. By age 40, these vital human building blocks have gone through about 610 rounds of replication, each with a chance for genetic error.