I am always perplexed by people who don't seem to know simple biology. I live in Iowa, which is a hugely agricultural state. We have lots of pigs and lots of cattle, but not many sheep or goats. I can guarantee that only piglets get born to sows, not calves nor kids nor lambs. Only calves get born to cows, not piglets nor kids nor lambs. I can also guarantee that only kids get born to goats, not piglets nor calves nor lambs. Finally, only lambs get born to sheep, not kids nor piglets nor calves.
The only crossbreed is the mule which is the offspring of a horse and a donkey. Mules are sterile animals and incapable of producing more mules. If you want a mule then you need a horse and a donkey.
In any event, after these various critters are born they grow up to become hogs, sows, cows, bulls, rams, ewes, and goats, according to their birth species. It is impossible for them to change or alter their species or gender after birth.
I find myself in a curious culture today where I could make the decision that I am really the reincarnation of the atman and nobody can disprove me. The fact that I can make this decision does not, in any way, shape or form, prove the veracity of the belief in reincarnation or of the existence of the atman.