From "Young Justice: Usual Suspects (#1.25)"
There's something I need to do. Something I need to tell you. Last month, on Thanksgiving, I went back to Cadmus. And found a few things out. When I was cloned, only half the DNA was Superman's. The other half was human. That's why I don't have - Will - never have full Kryptonian powers.
You sure? Cause you sure seemed to have 'em today.
I've been using these. Shields. They suppress my human DNA. I get the flight, the heat vision But I think I also get angry. Well, angrier.