Most dogs are the same, regardless of size, but yes, some are more dominant from birth.
The fastest way to gain dominance is to snap the leaash on the dog and tie the other end to YOU, nothing else just you. Second, always go out the door first. Always pick up the food bowl. Always stare him down when he looks you in the eye. Don't need to be mean about it, but win the stare down contest everytime. That goes for the wife too.
Just be consistent with these little things and he will come around.