Board Thread:False Info and Speculative Discussion/@comment-13895380-20150724155251/@comment-4091815-20150727212250

As with my earlier example - a horse and a donkey make a separate species.

So, no, you can't state as a fact that those two characters can't breed successfully.

While, supernaturally, one cannot be two things the current canon doesn't preclude that one could be a new thing made of two different things.