Hmmm...well I battled with DS2 for a month before I finally conceded he'd had enough. He started by biting me which I'm sure is a stage a lot of bubs go through. Then he eventually just kicked and screamed and flat-out refused to take the breast. Never in this time did I offer him a bottle or cows milk, I wasn't looking for the "easy route", I really tried to give it my best shot. It was when he was almost 11 months (after persevering for a whole month) that I finally gave him cows milk in a cup. I didn't force it upon him and he took to it happily. So I really do believe that some babies do wean themselves based on my own personal experience with DS2.