I've figured out the pattern!

The way births work, is they operate on a cycle of moon and sun. Psychic abilities are tied to the moon. As I was born at mere seven on a winter's night, I have merely scratched the surface of psychic abiliy. Which is why I can read people, but not all that clearly. Someone like Dawn must've been born at moonhigh. Same goes for Yakumo, or at least close to moonhigh. Those born in the day have no psychic ability (though sometimes the pattern, like any, is broken) and are basically normal. However, those at sunhigh are most likely to be born with....psychologic complications, we'll call it. (I don't want to say "problems", it sounds judgemental and I hate to sound judgemental because I'm trying to be nice). Liam-excuse me, Luna, was born at sunhigh. Mike, perhaps. Destinee, definitely, because I wrote her, made her up myself, and I say she was born right at sunhigh. That's the thing.
Twins (and triplets and whatever) are rarely born with one at sunhigh or moonhigh, though I've seen it happen (think Ghost Boy and his brother) it's exceedingly rare. They're more likely to be born in the day, and it's just a little bit less likely they'll come at night, though not totally unheard of. Those born at night, of course, tend to have stronger "twin telepathy" than twins born during the day. Of course.
I can't believe the pattern was that simple.