I got mine as chicks last year and handled them alot and they were skittish as young pullets so I was rather miffed. However with time they have changed. Perhaps others have already given you the answers as to why time changes them. But mine all fall along breed lines as far as personality.
Buff Orpingtons: Most docile and friendly as pullets. Now they follow all us "treat bringers" around like puppies, but never want to be picked up. Love to be hand fed. If I need to handle them, they do fine.
Rhode Island Reds: More bold and aggressive as pullets. I was afraid they were roos! Now, they are the first to come over to check me out if I "sit" with them (I do that, too), but they are more likely to peck at me and annoy me, seeing if my toenail polish or shoe laces or whatever is on my clothing is food. They do NOT like being handled and freak out and cause a fuss if you do. We have one that is a funny little nut, I think she is half bantam, and she will let me pet her and is our friendliest bird.
Russian Orloffs: Have always been extremely skittish, but will follow me around from a distance. Calm if caught and handled, perhaps because they FLY and I've had to catch and handle them frequently. Very difficult to catch however and I usually have to "herd" them like a collie!
I do think the fact that we brought the food over and over (and our feeder runs out daily) makes them love us and there is nothing personal about it. They do not like strangers however.