Where? I’ve heard that mentioned earlier today, but I don’t remember any reference in the movie. I don’t think anyone mentions Luke having any kind of offspring or romantic/sexual relationship (such a mention would have been by Han or Leia, I guess, and if they made such a mention it must have been drowned out by my popcorn chewing). I remember that first trailer (with the re-recorded ROTJ speech about Luke’s family) implying it, but where in the movie does anyone give any indication that Rey might be related to Luke? I’ll pay extra attention when I see the movie again on Monday.
Eh. I’m a good mechanic as was my father before me, but that’s because he taught me how, not because he sired me. Sure, those Skywalker genes might help one be an excellent pilot (the name sure is fitting that way), but the fact remains that Luke honed his skills in Beggar’s Canyon, while Anakin had podracing. If Rey has had any opportunity to fly at all before the movie starts, we’re not shown or told of it.
But that’s a niggling point, I concede. She can tell at a glance that a decrepit YT-1300 freighter is “junk,” and to be honest, I never thought the Falcon ever looked more or less junky than any other ship we see in the movies (except maybe for Padme’s ostentatious chrome ship in that movie I’ve mostly forgotten), but we’re meant to infer that she knows her ships. Or at least knows her junk. 
I just wasn’t convinced that she would necessarily be so good at flying one. I also think it’s kinda silly how much Abrams had the Falcon physically bouncing off the ground without sustaining any real damage, but also it’s not too believable having a crashed Star Destroyer and X-Wing sitting remarkably intact on the sand, when they are so easily obliterated in space. Another one of those “Enterprise in the Iowa cornfield” moments, I guess.
