I ask as this is an argument by many. It's genetic.
But I look at my cousin. He was adopted into my family. His biological mother was a heavy alcholic and his father a in and out of jail meth/crackhead. He met them when he was 20s. After one event of drinking far too much at 24 - as many young twenties do - he has never touched a drop of alcohol since. He's 43.
I admit that there may be a genetic issue resulting in a poorer ability to cope with situations or life which might be a mental health issue.
The reason why I say this my mother had an issue with drinking - poor ability to cope. Her mother - again poor ability to cope. Her grandmother - never touched a drop of alcohol & was phenomenal with her ability to cope with awkward, difficult, or hard situations.
From seeing parents drink or use drugs to how they react to situations. If someone's parent reacts poorly to a situation & then gets smashed (drunk) children are going to think this is normal behavior.