It helps me to think that it is natural for them to want to be with you. It is what babies need, to be with an adult all the time. There are lots of articles about it being genetics and children's natural urges to be close to an adult in case of emergencies and/or needing to be on the move. (Ie, many moons ago, if there was a fire or some predatory animal was around or something like that, then a baby/young child's best chance of survival is to be with an adult). It really makes sense to me.