Quote Originally Posted by thegreatonemal View Post
Nothing in the game ever suggests that there is trouble having kids between races. That's just something players have come up with to explain why we don't see the kids instead of the obvious devs don't feel like making more models.
2014 Las Vegas Fanfest Camate-Fernehalwes Interview:
Q: “Are there any folklore stories involving cross-racial relationships? Especially between Hyur and Elezen? And then, what do Roegadyn-Lalafell children look like? What is the fatality rate for such a union?”

Fernehalwes: “... As for the Roegadyn-Lalafell one, I mean, you know… First of all, logistically, how are you going to… I mean, I’m sure there’s fan art out there on the net. You can take a jaguar and a lion in a lab and do that. But the thing is, it doesn’t happen in nature, because some things shouldn’t happen in nature. But it could. I’m just saying, some things shouldn’t happen but that’s not saying it can’t. It can.”

the issue is more of a wailord on skitty sort of deal than some biological incompatibility like the other person implies. or to use non-pokemon meme example, chihuahua on great dane; they're unlikely to physically mate due to size difference.