My sisters never had to “let” me see them naked as if to satisfy my curiosity or to display themselves to “shock” me. Living as a large family in a small house.
My older sister explained she's acting that way because she's embarrassed that I seen her naked. So, little sis avoided me till she and the other went to the bus.
Yes, I am comfortable being naked around my brother, and he is comfortable being naked around me. Really, it's not a big deal being naked around each other.