Our pug Bruzer was fixed at 4-5 months old and had just begun to lift his leg when he was fixed. Gunnar our GSD is 2 and intact. He didn't lift his leg until he was 10 months old.
Should Gunnar have been lifting his leg at a young age as he was not fixed and was around another dog that lifts it's leg? On the other hand should Bruzer not lift his leg because he was fixed at a young age and was never around a male dog to influence him?
I don't think it has anything to do with dominance, fixed young, influenced by other male dogs, or anything. It just varies by individual dog.