x2... it seems some people get offended when you say it's not largely genetic, as if you're blaming them for their cancer. Well you know what, I just lost a dog to cancer and with what I know now about dog food, vaccines, and topical flea stuff, I'm at peace with the idea that I am mostly or all responsible for her death.
It sucks, but I'll be sure not to make the same mistakes again.
I do believe there is some genetic risk, but it's no where near what many think.
Just like Alzheimer's and Parkinson's by many is still thought to be largely genetic when in fact recent studies show only a 5-10% genetic component and even then only half those get it.