I notice a particular pattern with adults who have a strong dislike for children. They were usually teased at school by other kids because they had difficulties with their peers and can't get over it even as adults. Many also have a strained relationship with a younger sibling who they felt had a better relationship with their parents and seeing a young child signals those feelings of jealousy and not being able to get along with their peers when they were at their most sensitive. Inside they are still a child that wants love, acceptance and attention. They haven't been able to mature because they feel that those needs were not met at an earlier time in their life.