It's just lazy parenting - treating him the age he is would mean more work on her part. I have big age gaps with my siblings and whilst we did play together when we were little my mum definitely made sure she gave us exactly what we needed and spent time doing age appropriate things with us!I do feel for that boy as it’s clear he’s very babied. My 9-year-old is like a proper pre-teen, whereas Bill seems quite different and he’s always having to do everything the younger two do. Does she ever do anything just for him? He has different needs and should be really quite independent now. I know it must be tricky having quite large age gaps, but I can’t help but feel like she just includes him as one of the little ones!