His cheating at golf where honor is the entire point of the game is a window into his soul or lack thereof.

I am afraid that with his limited capabilities his mind thinks he can never achieve anything without cheating and lying. Probably he is right. But it is also very sad.

He's on the fetal alcohol syndrome disorder spectrum. He's never been right in the head. It's estimated that 60% of prison inmates are on the FASD spectrum. Classic FASD psychological and physical symptoms.

Mama was a rollin’ stoner… and his older brother got exposed to drinking somewhere

Was his mother an alcoholic perhaps?

There was booze abuse in that dysfunctional family and drinking while pregnant wasn't uncommon back in the day. There is no safe amount. Even one drink at the wrong time can cause damage to the fetus.