The Israelis have discovered that those who have a variant of a gene called AVPR1a on average give away nearly 50 percent more money than those without the variant at least in a game-playing/testing environment. Well, it is no surprise that people are genetically predisposed one way or the other. Of course, it doesn't mean that one cannot change.
This is similar to the finding that those with more highly developed frontal lobes in their brains are more unselfish and altruistic.
Can people change though? Are they mutable? Can they overcome predilections or predispositions, such as genetics? Absolutely they can. We know both first and secondhand. Whenever anyone stops doing a certain kind of sinning, that one has changed. It happens everyday. Plenty of people get into trouble, change their behavior, and then stay out of that kind of trouble thereafter. Every person is mutable. God can change anyone from his or her sinning condition. Just stick with it.