Everyone talks of genes as they would of fate or kismet: "It runs in my family", "It's genes, you can't do anything about it", "My mom had that, so I guess it's my fate as well", "Luke it is your destiny". Genes were though to be blueprints for your body and health.
We always knew that you carry many more genes in your body than you actually use (that is why two brown-eyed people might have a blue-eyed baby). And here is the fascinating bit --- scientists found out that many genes switch on and off. (This little video explains it very simply.) The body responds to things like diet, activity and stress by sending signals to activate certain genes and shut down others. This process is neatly explained here.
A small example of this is people's eyes changing colour when they switch to eating raw. So when it comes to your body, you have way more control than you thought. And you don't have to end up with your mom's anything.