I would say each yorkie will have its own personality. I know I was surprised that my little girl never once has chewed anything in the house ( I have had her since I picked her up from my breeder at 12 weeks ).. and all she seems to want in life is to be on my lap.. she will follow me through the house waiting for me to sit so that she can climb up on my lap. Once in a while she will bark at things.. the cat, the kids, my daughter's Chichauhau trying to instigate someone to play with her.. but for the most part.. she likes to lounge about in a lap like a little queen of sheeba.
If it isn't a matter of different personalities... the only other thing I can say is she gets as much exercise as she wants.. she has a big yard to play in.. and the house is large enough to afford running about when she wants to.
