Do all dogs mark? Do all male dogs lift their legs? At 11 mos. I haven't seen Loki lift his leg. Apparently, the dog walker saw him lift his leg once - she left a note that said "He's a man". He also hasn't marked anything in the house that I am aware of and he is locked in 2 rooms so I would know. He will quickly squat occasionally on a walk.
No, not all dogs mark, though most do in the right circumstances. Kodi was two years old before I saw him mark for the first time... He still rarely marks, only in areas that many other dogs have marked, like at a training facility or trial site. He has ONCE marked in a house... We went to visit a friend who had a bitch who was JUST coming out of heat. She also has a stud dog, and the two had been bred several times during that period. Kodi trotted in, said "hi" to his dog friends, went STRAIGHT to a drape against a big floor-to-ceiling window, and lifted his leg!!! I SUSPECT that the resident stud dog had marked their previously, but I don't know for sure. Both Dave and I JUMPED to stop him and tell him off, and HURRIED him outside. I am pretty sure he got the message, because he has never tried it again... even in that same house!
Both my girls will "over mark" where another dog has peed outside. This can actually be useful when I need them to pee in a hurry... (like at a trial) I lead them to a place where I know another dog has peed recently, and... voila!
Obviously, that could be a problem if you have dogs that pee in the house. so over-mark each other, but mine are well trained and we don't have "pee accidents" in the house that could encourage the others. This is another REALLY good reason to keep second (and third...) puppies CONFINED to easy to clean places during potty training. You CERTAINLY don't want the older ones back-sliding!