I loaded the game into a household and quit without saving... I wanted to change their Eyes with SimPE and forgot the step to change the eyecolor in the character files... I was wondering why it didnt worked and read the article again... stupid me .-. is this any bad? Or doesnt it do anything?

No, it doesn't do anything. A sim with wrong genetics simply wont pass them on if they have a baby while you play them. And if you did play them and the baby did have say painted on eyes you can fix the baby once they become a toddler. It isn't a corrupting thing its a visual.

Ouh thank you! I once heard that messed up DNA corruptes stuff... Well in that case it was when you take out Costum Eyes when Sims had them

Yeah it corrupts that sims genetics and any kids genetics they have, but it isn't hood corruption and its also easily fixed. I think a better word would be 'messes up' since corruption is a hot button word.