I've been known to do that. Hence, my ID of "Complexity".

For now, just consider the average between the two parents. That's what happens most of the time.

All the rest is just my fiddling with the few oddball cases that don't fit that pattern. Their so few, it's not a big deal to worry about. The only reason I'm even thinking of those cases is because I'm trying to find a way to get a black or blonde when I have neither.