Can Aliens Interbreed?

For "Crying on the Inside" here's a little bit more of the story.

(Actually, first I'd like to say that I haven't worked on it at all today. This morning I was busy composing.)

So . . . Where'd I leave off? Oh, yes. The escape plan. So Jack and Jadie are eating, and Keiki would be too, since she and Jadie are both on the "same" schedual. What I mean is that they eat and sleep at the same time. All their different "periods" where they work are compleatly different. And Jack is just following Jadie around.

Jack's plan is probably going to involve killing a lot of Lieums, or at least the ones who get in the way. But the Kinssa are inheirently good, as I've said, and they all know that killing is wrong in almost every case. (Or maybe every case, but if someone's trying to kill you I think they should be able to do something about it. Poke 'em in the eye or something.)

There'll probably be some kind of fight, but I don't know yet. After all, I skipped a bunch to get to the Marky and Offer scene.

Okay, the last thing going on the main story, the one that doesn't jump scenes all the time is where Jadie has 'garden' and is talking to Jack about why there are no half-breed Kinssa.

What's gonna happen is Jade's gonna say that some different aliens can interbreed, such as the Nohnay (or None, as I like to call them) and the Kinssa. But they have a commen ancestor. (Actually, if I remember correctly, the Nohnay are half Kinssa and half human. Maybe Jadie doesn't know that.) So Jack asks about the Lieums. Jadie says that they can't interbreed with the Kinssa. "Trust me. I know."

How does she know?