All I know is that, according to Wikipedia, Freddie Trump's alcoholism was so bad by 1970 that his wife made him leave their home and got Trump Sr. to agree to change the locks. And Donald was only 24 by then. I could definitely see him being against the whole idea of alcohol by the time he got to his teenage years if it was that bad by then. Donald is eight years younger than Freddie.

https://en.wikipedia.org/wiki/Fred_Trump_Jr.#Alcoholism_and_death