Birdo is a man that identifies as a woman, and she pulls it off so well that Nintendo of America fell for it.
End of story.
Yoshi is the more confusing case, since he is a male that lays eggs. But I guess that's just how the Yoshi species works. It's rare, but possible, and other species work in similar ways in real life.
So they're both biological males, one identifies as a male and the other identifies as a female, and they're happy together. Does that make Yoshi gay? It depends on whether you think sexuality is based on the sex he's attracted to or the gender he's attracted to. Either way it's a cross-species relationship, and that's the only part that grosses me out.












