I'm not sure about the DNA thingy though, maybe it has, but I think it's probably on what they see on their parents that is pass from generations to generations, not DNA per se. If you see you parents at a young age, have gambling sessions in your house (this is prevalent is Asian Culture, playing mah-jong). Definitely you can inherited this as you grow old. So it is still the environment that is the influencing factor and I think majority of gamblers some kind of interaction or exposed to gambling when they are very young. But we have a choice, whether to fall victim or not.