it's extremely rare
it is unfortunately true that they often chop the boy parts and treat them as a girl though
which is no less sexual mutilation than circumcision, which is abhorrently acceptable in modern western societies even though it's about as brutal an unnecessary medical operation as you can get
also i think that 0.5% is probably overstating it
if this kind of thing was even remotely common it would also occur regularly in many other mammals and it doesn't
“[it] has been reported in mammals, fishes, nematodes, and crustaceans”.
“[it is] estimated that [up to] 1.4% of pigs are intersex … [up to] 1.7% of humans”.
