Can he or can he not flip?

According to the babysitter, Gabriel can flip over. However, after observing for several days, he doesn't seem to be able to flip on his own.

Provided he is in the mood and has enough energy to overcome his heavy bottom, Gab can flip over --> on condition that I give him the initial push. Otherwise, he's very much happy sucking his thumbs.

I think I've got a lazy son...