My daughter was the same way. I believe it was laziness, so to speak. There was no doubt that she was very capable and able to hole the bottle on her own, but, she just refused to do so. I tried everything, from tucking a towel or something underneath the bottle, and everything in between, and she would let go of the bottle, or she would knock it away, just so I would have to hold it for her. I would have to say, it is a strong will (stubborness?), and it was very frustrating for me. I knew she could do it, she just refused to do so. She lets go of the bottle, because she wants you to hold it! You have a strong willed daughter. That is all that is to it! Good Luck.