I think this object issue is like the nature/nurture discussion- it's a bit of both, mixed in differing proportions for each child.
My 4 yr old dd is very intense- I've often said she needed two or three mommas- and she usually has at least one object with her in bed or in the car. I can gauge her reaction to a particular situation by how many animals she's carrying around. For instance, When I was prego she carried around six or eight animals most of any given day. When I came home with baby, she dropped them and just wanted me. My 21 mo old has a few favs- a doll, a fox, and a postcard with Jesus on it. She wants them in bed and now wants them in the car, in part because she sees her big sister doing it.
I EBF, cosleep, SAHM, sling my babies, respond to cries, so on. But my kids like their security objects, esp. the intense dd. At times I share bed with dozens of animals, like before she had surgery. Right now she carries a whole bag of animals because she saw a housefire in our neighborhood and now she's worried about her toys.
gotta go-sleepy kids--