How often do the different Races inter-mingle with each other?

[myahele]

It seems to be a lot more common among adventurers since it's pretty much part of their profession to accept work from a whole lot of different people from varying races/ cultures. In fact, many adventurers npcs we run across have been multi-racial: Edda's crew, that other crew we saw near the beginning (roe, miqo'te, lalafell) and everywhere adventurer npc hang out have been multi-racial group.

Here's an interview that's kinda relavant on this subject matter:

MCKF: I touched on this a little bit today in the live stream and there was a question about relationships between the races and crossbreeding. A lot of it doesn’t happen because while we have all these races living together in Eorzea, there’s this tension between them. That’s there because they have these histories of fighting for a long time and then not really making up, but agreeing to disagree and living together because it’s better than living by our self and being more susceptible to Garlean attacks or whatever. We work together because we have a common enemy type of thing. Most of the races don’t really like each other and it”s gone on through multiple Eras. There are times when Eorzea has been more populated by one race over another and there will be conflict there. With the Hyur and Elezen, that’s very recent. In the sixth astral era, Elezen migrated in and in that era they were like “we’re the first ones here!” even though they weren’t, but they were the first at the beginning of the sixth astral era and they settled and of course the pesky Hyur who are everywhere come in and the Elezen are like “oh my god we left you that whole continent up there why are you here!” and the Lalafell come in and you have these cycles of clashing and moving part and that gets ingrained in their society and their racial cultures. There’s always these power struggles, you’ll have times when the Lalafell rise for whatever reason and they’l side with one group and then turn on another group and that’s one of the reasons there’s not a lot of interracial relationships because even though they’re living in the same towns it’s like well yeah… but you’re an Elezen.

F: I can just imagine some young Elezen bringing home a Hyur woman and the Grandma going “Why couldn’t you have found a nice Elezen girl!”

MCKF: There’s a lot of that going on. Like i mentioned in the stream, in the future we’ll have some characters that are half one race and half another ...

http://gamerescape.com/2014/10/22/fa...pher-koji-fox/

With that said, we pretty much have to keep in mind that Eorzea Alliance we see now (as well as adventurers) are came to be roughly 15 (?) or so years ago. Prior to that:
1. Gridania was Isolated
2. Ishgard was was roughly the same
3. Limsa was not the limsa we know under Merlwyb, it was a pirate capital
4. Ul'dah speaks for itself

Other than trades, there were not that much interaction between the city states themselves.

But if I were to guess, midlander hyur- elezen relation in Gridania is great. It's the basis for how Gridania was founded.

Ul'dah once had a hyur (Thorn) Dynasty ruling over.