Identical Twin Brothers?
I am a twin. As a result, my twin and I have literally been nude together since before we were born. Then, we shared a crib. A room. Baths. Bedtimes. Wardrobe changes. Everything. We were nude together a lot of times, and really never thought anything of it, even though the rest of our family is very much not nudist.
Still, to this day, we are comfortable nude together. While they're not a nudist, it's never an issue when I'm nude - it's just as natural as when we were in the womb together.