When children – most commonly boys – are not able to get their cup refilled consistently they often become impulsive and inattentive. Other children, more commonly girls, can become timid and mousy because they are not allowed to be assertive or independent. It’s the tabletop experiments all over again. The only thing some boys know how to do when they are frustrated is be aggressive; the only thing some girls know how to do when they are frustrated is to sulk or follow passively along.
From "Playful Parenting," by Lawrence J. Cohen: Pg. 145 –