Again, that's not how our modern understanding of genomics works, and hasn't been since the 1980's. There's much, much more to it than genes+environment. See all the mechanisms I've mentioned in GP. Also, you brought up 'variation between people', which can be aditionnally confounded by things that have nothing to do with DNA at all, such as the various microbiomes.
It's important to note that heritability is not some kind of magic bullet that explains everything with "genes". If you want to convince a biologist that "genes" are the cause for a given phenotype, you've got to show an actual genetic causal mechanism or you've got nothing. This is, again, due to the myriad of interfering mechanisms that make "genes" very, very removed from the actual phenotype. And again, I'm not talking about the environment.