Dear Rabbi,

You recently wrote about the hypothetical case of a kosher animal genetically engineered to give birth to a non-kosher animal. I have a different question. What if a fetal pig was placed into the uterus of a cow?

Dear Meir Balofsky

Even if such a fetus came to full gestation and was born, it would be forbidden because it originated as a pig before being put into the cow. The rule that "anything originating from a kosher animal is kosher" means anything produced by a kosher animal. In this case, the fetus was not originally produced by a cow.