As men get older, their DNA matures—and when that genetic material is passed on to children, it may mean a longer life for the kids, researchers find. Thus kids with older dads and grandfathers may be "genetically programmed" for higher life expectancies, the BBC reports. It all comes down to telomeres, the structures that protect the ends of chromosomes. Telomeres in the majority of cells shrink as they get older—but it's the opposite with sperm cells.
In sperm cells, telomeres get longer as a person gets older; if these longer telomeres are passed to children, it can mean longer telomeres, and longer lives, for the next generation. A relatively old paternal grandfather can mean even longer telomeres in a child. If fathers keep having children at older ages, it could mean longer life expectancy for the greater population, researchers say. But that doesn't necessarily mean men should delay having kids: Doing so boosts the risk of miscarriage. (Read more fatherhood stories.)