I kind of feel dumb at the moment… I was researching breast cancer, and it said that there is a 50% chance of passing the breast cancer-risk gene to the offspring, if the mother has it… Now, I thought each parent had 1 dominant and 1 recessive gene for each trait… Assuming the mother is heterozygous, and that the gene was dominant that caused a risk for cancer, wouldn%26#039;t that make it a 1 in 4 chance of passing the gene to the offspring? If so, why?|||The gene for breast cancer - BRCA1 + 2, is dominant. Therefore it is a 50-50 chance of transmission.

I just made this image to show you why its 50-50…

http://img87.imageshack.us/img87/5109/cc…

C = Brca

c = normal gene

Therefore 50%