I too believe there is a genetic component.
Back in the 70’s as teenagers me, my brother and cousin would routinely drink ourselves to unconsciousness, funds permitting, once or twice a month. My cousin’s parents were alkys themselves so there was no supervision.
The next morning when we all woke up the first thing my brother would do is go to the refrigerator to see if there was any beer left.
Me OTOH, when I was hungover I would react to even the sight of alcohol the way a vampire did to sunlight in those old movies.
Nothing at all to do with willpower or personality, hadda be genetic.
Both my brother and my cousin hit rock bottom in their time. Both of them now swear by Alcoholics Anonymous, turned their lives around. My brother met his wife there and it’s been a great marriage.
I’m very sorry to hear of your son but there’s hope.