That’s funny, my oldest was too. Daily scotch(es).
I can’t say it’s ALL in the genes but that’s the foundation, be it sturdy or shaky, particularly for resistance to gneric disease. Most people are born near average on the baseline healthy scale...after that, who knows.
Weight: Inhaling junk food & sugar on the sofa with your phone is going to make most anyone pork up.
Metamorphasis: The scrawny kid in the old comic book ads getting sand kicked in his face at the beach by the bully can buy & lift weights all he wants but 9 out of 10 are still going to remain mostly scrawny.