Old generation can raise gambling habit on young or current generation, if that old generation has achieved something in gambling. If persons grandparents or great grandparents simply gambled from time to time or did it frequently, then future generation wont have any impact because of that. But, if relatives have won in a lottery, got lucky and caught jackpot, or simply won a huge amount, then this might trigger future generation to start gambling. There is no such gene as «gambling». It is not passed on from generation to generation.
I agree with your opinion, that there are no genes or hereditary gamblers, but gambling is a habit of someone who has done it, whether for a long time or recently, and this behavior will make someone addicted because there may be two factors, namely hobby. as entertainment or at the same time making a profit so that you are addicted to continuing to do it.
Therefore, the older generation may have experienced what I said above, and this will trigger the younger generation to try gambling because they only saw or perhaps heard stories from the previous older generation.
there may be no hereditary gamblers, but if a person is continuously expose to gambling related activities, he may form a habit as well. but if they will see it on an occasional basis, like when your football or basketball team is playing, i don't think such young person will be a habitual gambler. they will more likely see it as a form of family entertainment or bonding activity among family members.
also, if a young person may see his older family got addicted in gambling, and got so much troubles, either he will follow the steps of that person or change his path not to have the same kind of life. this will depend on the person himself, it is by no means in the genes of the person to be a gambler.