My Father was/is in the Merchant Marine, so he didn't join the military.
My Grandfather was very active in the Norwegian resistance during ww2, and in the Army the rest of his life.
His Brother was a Wing Commander Flying in RAF during WW2, but got shot down at the end of the war.. (was ready to go home, but volunteered for one last mission. Shot down over Holland..)
And their father was in the Army as well, but not his whole life..
And before that??? Don't really know..