Alcohol and genetics

Do yall think genetics play a factor in people who can drink for years and not have a single problem health wise? For instance we have a family friend of ours who is 73 years old and drinks about 4 handles of vodka in a 2 week span and smokes around 7 cigars a day (who used to be a 4 pack a day smoker) despite him being crippled and depends on a walker and a wheel chair to get him around with all his health problems none has to do with liver kidney or heart issues almost seems as if he’s in better shape when he drinks and smokes according to my dad he has been heavy drinking since he was most likely in his teens and tells me several stories of his heavy drinking and drug use in his young years. He’s full blooded Irish so that be part of it but I almost find it impressive that he’s still kicking at his age drinking as much as he does so is it just a genetic thing for him or is it just pure luck of the Irish?