Can someone please explain the ethical implications of cannibalism?

If someone found a way to creep into my house and kill and eat my children, then I would be rather distraught, and rightfully so. I'm not sure the reason why I'm disgusted by this scenario and not by pork chops, for example. There is a taboo against cannibalism in our society, but does that necessarily mean it's wrong? For example, growing up I remember the pearl necklaces that were made from oysters, but now we don't do that anymore. I'm not sure what the ethical implications of giving oysters pearl necklaces, but the point of this example is that there are things that aren't necessarily wrong, yet we don't do them anymore. What do you all think?#####Edit: Thank you all for the fantastic answers!! I have a better understanding of this topic now.