great question, & responses. my contribution is from experience & i'm sure specific to my dogs. i do have to say my ollie (yorkie) is different than any other dog i have ever owned & i currently have ollie & my mix mallory. raised both the same & ollie is more skiddish, needs to be around people appears to make him feel safe, he dosen't like to be outside as much. my yorkie just is more "baby" like. i love it, he acts like a dog sometimes but think he learns a lot from mallory, lol. all dogs are awesome!!!!!!