DS has been able to roll belly to back since 2 months. He didn't roll back to belly until 5 months and still doesn't do it very often. He has done it so I know he can do it but he just doesn't want to. He prefers to be on his back and now that he sits well, he likes to sit up. I just wonder how he is going to learn how to crawl if he is not developing his upper body strength by rolling. We still do tummy time and he still hates it. My first ds was rolling around the house at 4 months and DS2 has never rolled like that. He is meeting every other milestone on time but he kind of skipped rolling. Anyone else?