What do you think?
http://www.genengnews.com/gen-news-highlights/dog-fear-and-aggression-genes-related-to-human-anxiety/81253083
We may soon be able to test our dogs so that we can produce dogs without fear or aggression. The only aggressive Havanese I've ever seen was from a puppy mill and may have had other breeds behind her. I have seen a lot of very shy Havanese which could be genetic and also environmental.
I was told by one of the original breeders of Havanese that they use to be so shy that they couldn't be shown by anyone other than the owner. They've come a long way since then!