Well, there was actually an art contest not too long ago that dealt with the TMNT's offspring. We weren't saying it was possible, or should happen in canon, it was just fun to set the boys up. Wait a sec...
http://www.behindthemasks.com/greenw...antentries.htm
There we go. It was so much fun. And there are probably twice as many hybrid pieces out there that weren't entered (I know I had some extras.) In the case of most hybrids I tend to believe that the child will most closely resemble the mother's species, since she needs to carry it (in most cases) and it needs to be close enough to her to avoid miscarriage (sad truth.)
I still think the TMNT alone in the world is a very good theme, and I hope they draw that angst out to it's highest potential. But it's fun to play, and no offense is meant by this. We still love our turtles the way they are.
As for the individuals:
Leo: Boy, definitely. Just as driven as Leo, honor-bound, but knows when to bend. But it's really funny to see him try and talk to a girl.
Don: Boy, basically a chip of the old block. Genius, engineering skill, philosopher, but he knows it's not his calling, he just can't figure out what is.
Mike: Girl, pretty and sweet. Appears quiet and naive, but actually is quite intelligent and shrewd if need be. Daddy's little girl.
Raph: Girl, once again, a Daddy's girl. Got her father's temper (and her mothers. Eesh!) but has learned to focus it instead of losing it. Oddly enough, she's very feminine, adding little touches whereever she can without sacrificing praticality.