I used to watch a cool cartoon about two men and two kids who had all sorts of adventures. One man used to wear a green shirt and had a beard( he was a scientist or somthing) the other wore red shirt and had fair hair ( this one was a tough guy). One of them had a son and the other had a daughter. If that rings any bells please let me know.

Thank you!

All I can think of is Johnny Quest, but it has 2 boys not a boy and girl. The description of the Dad( beard) and tough guy fit exactly.

Yeah! That's the one! Thank you very much. I looked it up and the girl I mentioned is the tough guys daughter who only appeared in "'The Real Adventures of Jonny Quest". Those are probably the series I watched.
Thanks again.

The fantastic and rather twisted The Venture Brothers on the Cartoon Network is both a spoof of and homage to Jonny Quest. Highly recommended, but it plays out like the R version of the original series, and most of the characters are jerks or failures.