It is not as straight forward as is there a gene yes or no.
The only 'conclusive' studies as such are those where you can establish that those people with the same genes but who have grown up in different life circumstances go on to have diferent lifestyles.... so those with an alcolic father do not have a predetermined life chance of being an alcoholic regardless of unbringing.
The difficulty with such studies is two fold. One. Tracking people over a long period is difficult, costly, and studies often lack validity. Secondly, studies usually need genetically equal comparators in different situations, ie adopted twins separated at birth. At best extremely rare, at worst, unethical.
Without those studies (there's one Kajj, I think), it is really hard to tell what is nature and what is nature. The brain and consequently personality and behaviour will be constantly changing, with some genes being switched off and others becoming more important (epigenetic). Certain character traits will dominate for example competitiveness, risk taking that trigger the release of brain chemicals endorphins, that promote certain behaviours (relaxation, calmness, pleasure). That creates a cycle craving more excitement, risk taking, adrenaline fueled behaviour.
There's no point worrying what genetic inheritance you've given your children. Some kids will create that dynamite themselves. Rather, you've given them a headstart in knowing what to look out for, by giving them an awareness of excitement ahead from their ancestors. Whatever that behaviour, or propensity to alcohol, or drugs, or gambling, or religion, or whatever was.