Stigmatization is no joke this very issue of alcoholism plagues the uncle of a close friend of mine and till this day it is still associated with the family name. I once asked my friend if he takes alcohol, he instantly shouted no because he does not want to turn out like his uncle
He probably remembers and associates such questions with the situation of his father that's why he was so quick to clarify you.
I believe time will tell but it's also a good thing that he tries to stay clear from that same thing that has stigmatized the family
Thank you for your input and reading my post @coderaikiri