Just a thought...I was watching "Roots", wonderful series BTW. Just wanted to say how realistic it is. And I love realism. I can't help but think, I wonder, do comics ever really show the effects that all the drama in heroes lives has on them?
I just saw a scene in "Roots" where a character who was once a slave won't allow his daughter to marry a light skinned black guy. Only because of his experiences as a slave, where color was a status symbol, the darker you were the worse you were treated. So he was bitter after all those years, even though his daughter's situation was not exactly like his.
Just goes to show that in fiction, the past does and should matter. Things that happened should have a bearing on how characters act. Although it is all too easy to force what you want to happen instead of taking this into account. Not to say every situation is PSTD, but nonetheless characters ARE what they were and THEN some.
Now this is just about personalities. I NEVER would advise you to be totally realistic with science and physics, because doing that is just near impossible. With superheroes, believe me I have tried. It's a losing battle that will take more work and give you less variety than the comics have by far.