My (non-identical) twin boys are nearly 8 weeks old. One of them was born with lots of hair, and ever since he was about 2 weeks old he has grabbed it and pulled it - hard! It obviously causes him pain, because he screams blue murder whenever he does it. I can't identify any obvious trigger - tiredness, stress, etc.
Has anyone else experienced this, and what did you do about it? At the moment, I've just put him in a hat!!