I think it's not a univariate problem. Our society is plagued by people who desperately want to simplify every problem into a univariate issue.

Genetics has an influence, along with many other factors, because reality is multivariate and complicated.

My twin is significantly overweight. Has been since we were 15. I'm not and haven't ever been. I always enjoyed working out, he didn't. Your univariate view of the world can't explain this.

My twin converted to Mormonism a few years ago. I'm not religious at all. Does genetics explain this?

Starting with our college years, he and I have divergent life experiences. I fathered a child at a very young age, and the child was born extremely premature, and I was subjected to a life and death medical crisis at this age. He wasn't dealing with that. My father views this as being a tremendously powerful factor in our rather potent differences today.

I don't seek to be antagonistic, but my entire life story defies your thesis. Doesn't mean you are wrong, but it certainly means that you are "overfitting" in the classic statistical modeling sense.

And to be fair and defend big chunks of your thesis, my twin and I do have a lot of similarities in our lives that are probably strongly influenced by genetics. But one thing we agree on is that a massive factor in both of us being successful is our difficult childhood. My mother was a schizophrenic who left us when we were toddlers, and doomed my father to raise 5 kids by himself. Our family's income put us below the poverty line, and we were subjected to a lot of trauma and occasional abuse when my father would relapse (alcoholism).

Coincidentally, my brother's ex-wife was a genetic determinist, and a big point of friction was her constant projection of our family history with mental illness onto every behavior she didn't like from my brother or myself. He got a small tattoo on his arm for his 35th birthday(against her wishes), for example, and she attributed this to mental illness. Because that's what univariate thinkers do: They explain reality with a univariate model, and make everything fit that. It's a shitty model, and if it was productized for data science reasons, it would fail miserably.

> My twin is significantly overweight. Has been since we were 15. I'm not and haven't ever been. I always enjoyed working out, he didn't. Your univariate view of the world can't explain this.

Yes it can. You were subject to different environmental factors. These differences can compound to produce very different results over time, but ultimately it is still genetic at the root.

I could respond to the rest of your post but I think this is the crux of your argument.

My twin brother and I shared a bedroom from birth until we left for college at 17. Exactly what different environmental factors can you identify between us that would have made him chunky at 15 when I wasn't? Or that made him not enjoy exercise and sports like I did from the age of 8 onwards? Are you going to admit that it pokes massive holes in your univariate theory, or simply continue to double down? Perhaps my side of the room had a dramatically different climate than his, right? It's as if your brain ignored the obvious to continue to support your absurdly simplistic genetic determinism.

It seems like your argument is now "there were differences but there's no way they were big enough to change how we developed". Unless you've got understanding that vastly exceeds current science, I don't think you can say which differences are relevant.

Biology and chemistry exist as disciplines because, even though the laws of physics theoretically explain everything about the universe, it is completely intractable to use them to do so — and it turns out we can construct explanations of the universe at higher levels of abstraction than fundamental physics, and then reason using those explanations.

Your argument seems to be that physics is all we need.