Why is EVERY SINGLE teen created by the game MEAN?

I'm sick to death of sending my teen to high school only to find a couple of new students and Every. Single. Time. they have the mean trait.  I'm constantly editing them to remove it and I'd like to know why EA think literally every single teen is mean.  I wasn't as a teen. Neither were my friends.  Neither are my sim teens. So cut it out, will ya?