I don't know if I am doing something to cause this myself, or if it is just random but mean streak is my least favourite childhood phase (they all annoy me a little bit, but mean streak is the worst) ...
All this just makes me more certain to avoid the Parenthood pack! Also I can make a "bad" teen Sim and even a "fight club" on purpose, but I wouldn't want it visited on my Sims' childhoods as part of an inevitable phase.