Cow Milk

No, not genetic diseases, and not cancer, either. The problem is systemic infections, like HIV. There are tests for those. BTW, women who can't nurse their own babies can get milk from volunteers. Any attempt to commercialize it would be shot down by the anti-sex lobby (titties are all about dirty, filthy sex, dontchaknow), which is mostly driven by the Cult of the Cross, even though there's nothing in the Babble about drinking human milk after infancy.