The official stance I believe is that while half-breeds happen, they are rare due to cultural differences between the different races. Judging by the fact that we've never seen a Lalafell with cat ears or a Hyur with slitted pupils in game, one can assume that they take the race of either parent, not a mix of both, when it does happen. At least, that's how I see it for now.
Anyway, welcome. I'm all for more Hyurs personally, there's just not enough of them~ Play what you'll enjoy!