Fathers who only have daughters could be at an increased risk for prostate cancer.
According to researchers at Columbia University, it may have something to do with a Y chromosome defect.
A child's sex depends on whether he or she receives an X or a Y chromosome from the father.
After studying more than 38,000 fathers, researchers say men who had no sons at all had a 40 percent increased risk of prostate cancer and the more daughters they had, the greater the risk.
However, experts say more research needs to be done.