Researchers have discovered men are carriers of a gene that can cause ovarian cancer.
This not only raises their own risk of developing prostate cancer, but also increases the risk of their daughter getting ovarian cancer, the Daily Mail reported.
It is the fifth-leading cause of death for women cancer patients.
Scientists are now able to understand why women are more likely to get it if their sister has it than if mothers have it.
"A better understanding of the inherited genetic risk of ovarian cancer from the father's side as well as from the mother's side is vital for helping women to determine their individual risk of developing the disease and to make informed choices about preventative strategies, including surgery, " Annwen Jones, chief executive of Target Ovarian Cancer told the Daily Mail.
Fathers pass it through the X chromosome from grandmother to granddaughter.
"Our study may explain why we find families with multiple affected daughters - because a dad's chromosomes determine the sex of his children, all of his daughters have to carry the same X chromosome genes," lead author of the study Dr Kevin Eng, told the Daily Mail.
Adding, "What we have to do next is make sure we have the right gene by sequencing more families."