Ah, but have you considered the fact that he's undergone a sex change operation, and was actually originally a female, the birth mother? Elementary, really...
I wonder if this interpretation is a result of attempts to make the model more inclusive than the corpus text, resulting in a guess that's unlikely, but not strictly impossible.
I think its more likely this is just an easy way to trick this model. It's seen lots of riddles, so when it's sees something that looks like a riddle but isn't one it gets confused.
Indicates the gender of the father.