[justinjlynn]

Generally, individuals with the XY genotype but the female phenotype have an additional genetic anomaly which renders them androgen insensitive. Therefore, I would say that, in most cases, the sex of an individual is fully, or at least a fully as possible, genetic. It's just not as dependent on the presence of an X or Y chromosome as one would think.

I suppose you could induce something like that by treating an embryo with finasteride or another SARM but there's a reason such drugs are in pregnancy category X. They tend to produce wider ranging and more severe defects than just changing the sex of the embryo. Hormones are complicated.

[omginternets]

Fair enough, but then it should also be possible to environmentally affect gene expression. I'm clearly nitpicking insofar as sex is overwhelmingly determined by genetics, but I feel it's important to hammer in the point that "everything is nature and everything is nurture".