
I also think that dog experience goes a long way here. With no disrespect to new dog owners intended. A novice dog owner, being a bit unsure, would communicate that hesitance to the dogs. They ain't daft!
Brainless, having humungous dog experience sorts it with an ear bashing.

Don't you just love her way with words? But seriously, it pays to know your breeds, and to be on top of any altercations.
Having such a lot of dogs, all living in the house, I often get asked "what do you do when they start fighting?" My reply never, ever changes.
Any growling to be done, and I'll do it. That isn't so much about dominance, but more about being "in charge." If I had breeds that I am frightened of it just wouldn't work. I only have experience of Pastoral breeds and Toys. It's what I'm comfortable with, and I am sure that the dogs feel that.
If I could only have 2 dogs, yes it would be one of each sex. Although I find males so much more affectionate than the girls.