1. Four and a half might seem like "practically an adult" for modern men -- after all, they're ready to be away from mom & dad for 7 hours every day, right? But keep in mind that many ancient cultures practiced extended breastfeeding with little boys and girls his age.

2. Related to #1, in the Old World, children under 5 are considered and referred to as "babies". The word for "child" in French is "enfant".

3. Keep this in mind as you consider the appropriateness of thumb sucking, attachment to blankets, etc. at that age. Just think that many boys his age are breastfeeding (for comfort). The least you can do is offer him a substitute, for his emotional health's sake.

4. Under age 5, there is very little difference between boys and girls. About the ONLY difference is in the "plumbing". There might be subtle differences, but most of the major differences between the sexes aren't apparent until later. That's why having male teachers for boys is important *after a certain age*, etc.

5. There is very little objective difference between a "stuffed animal" and a "doll". Why are "dolls" only for girls but little boys can have other kinds of "dolls" as long as they're called something else? A rather artificial construct if you ask me.

6. There is plenty of anecdotal evidence of young boys experimenting with "playing with dolls" when they are younger. Particularly only children and boys with lots of sisters. Usually when they're very bored. They usually discover it's not for them and move on -- provided no one makes a big deal out of it.

7. Don't make a bigger deal out of it than it is.

Since this is not your child, but your daughters, I think you should stop meddling and mind your own business.

OP- So far he's an only child.  His cousins live hours away, and he doesn't have the opportunity to play with kids his own age that often. All the kids at church are either babies or much older. There are only a couple of kids he gets play dates with once in a while. We do a lot of stuff together to keep him occupied, but I know that doesn't replace a playmate.

Just a couple of thoughts. If he had siblings they would be either younger or older. Why is it a problem that they are not his age?

Why the need to keep him occupied? I may be wrong but people tend in this age to feel they have to keep kids busy, instead of letting them develop their own resources through fantasy and imagination.

I think he may pick up on this anxiety and respond accordingly, by clutching at his security too.

And lastly, are his parents desiring another child? Or putting it off for some reason?