I’ll cut straight to the chase.
I can’t prove, nor can I disprove this notion, and I don’t think science can either at this point but I can provide some really good insights for you.
1) We have yet to identify any ‘big’ or ‘small’ or ‘fat’ or ‘skinny’ gene or genes, or combination of genes.
2) But this doesn’t mean that it doesn’t exist…
3) Even if they did, that’s not how Genes work within human physiology.