You don't have children and have no plans so let me let you in on a little parenting secret:
Never tell other people how to parent their children.
I'm not gong to bother touching the idea you've got in your head that social media is an addictive substance but tv and movies are not not the idea that tech withdrawal is anything like drug withdrawal.
Correct. Largely genetic to the point there are specific genes that are link to it.
The early drinking part is likely because they are being raised by alcoholics so access to easy and possibly encouraged.
Claiming early drinking alone is responsible for alcoholism is about as meaningful as blaming early marijuana use to drug addiction.
The path to the destination may leads through certain steps but does not require those steps. There is a reason many children of addicts choose absolute abstention.