Men who father daughters, not sons, may be at a greater risk of developing prostate cancer
The Israeli team found men with three daughters and no sons were up to 60% more likely to develop prostate cancer.
But the Journal of the National Cancer Institute study suggests the cause may be the male "Y" sex chromosome, not the act of having either a son or daughter.
UK experts said a common genetic cause may affect both cancer risk and the chance a man will father girls.
Prostate cancer is the most common male cancer, with more than 30,000 new cases in the UK in 2003.
It affects the prostate gland, which is found near the bladder in men, and produces one component of semen.
The Israeli research looked at more than 38,000 men, and compared the families of the 712 diagnosed with prostate cancer with those of the other men.
Overall, compared with men who had at least one son, those with only daughters were 40% more likely to develop prostate cancer.
The risk increased when a man had three or more daughters and no sons.
No wonder many men prefer sons!