There are lots of ways to inherit cancer risk. for example, when discussing breast cancer risk we focus on the mother's side (The Gail scale) very often it is the paternal side that is actually conferring risk. It could be that 5% of the risk is from the paternal side. There is a risk model that incorporates about a half a dozen risk models to be able to capture as many factors as possible.Actually other studies have been done using paternal data, like the studies that tried to identify the purity of the genetic line of certain gypsy populations. And family history of risk of Alzheimer's confers risk, however those with mothers with Alzheimer's are at more risk than those with fathers who have Alzheimer's.The genetics of disease is extraordinarily complex. We do inherit two genes but through a principal called imprinting we may only have one of the two genes turned on. So when amassing your family history, be sure to get the history from both sides.