Question

Explain how breast-cancer genes are still present in the population, despite cancer-related surgeries and deaths.

Answer 1

Perhaps this might be explained by the fact that the many cancers affect individuals after they have passed on their genetic information, so there is no advantage to those not carrying cancer genes. Also there are a number of factors leading to cancer, so exposure to environmental factors might also be necessary for cancer to develop. Hence there might be no pressure to lose the cancer alleles.