“[We] found a strong trend for a decrease in prostate cancer risk as the number of sons increased," said Dr. Susan Harlap, study author and professor of clinical epidemiology at Columbia University.
Since girls, by definition, only get an X chromosome from their father and not a Y, Harlap and colleagues believe that having no sons may be an indication that a man has a defect on his Y chromosome. Therefore, the more girls a man fathers without having a son, the greater chance that he has a problematic Y-chromosome. The defect, they suggest also increases a man’s risk for developing prostate cancer.
“Our findings suggest that the biological significance of lack of sons—whatever it is that leads to increased risk of prostate cancer—becomes increasingly important as family size increases," said Harlap, who added that while her findings are consistent with the idea that a Y-chromosome defect raises the risk of prostate cancer, other explanations are possible.
For example, a man who had two sons and no daughters, had an 11 percent increase in the rate of prostate cancer, compared with men who had one son and one daughter. But Harlap believes this finding simply shows that chance, too, plays a role in prostate cancer development.
Moreover, the authors add, women tend to be more health conscious than men, so having many girls may make it more likely for a man to go for prostate cancer screening, making him also more likely to get diagnosed
