I doubt it's connected in a physical sense but I would not be surprised if the eating is more to do with how much independence is encouraged at home. If mom is trying to keep him a "baby" she may also be feeding him and if it's their first child they may be a little slower at introducing new things. My 4 yo still sucks her thumb when she's tired or while sleeping. If it is in her mouth during the day she is just reminded not to suck her thumb. It is a comfort thing for her.