Nope, that’s cultural. That uneasiness and feeling in you stomach “something is very wrong” and that children are uneasy around nudity is cultural. A different flavor but the same thing as people teaching kids to freak out around gay people.
I remember at 9 years old in the south of the Netherlands, using the sauna area of the pool complex. That was a nude area for everyone. In the rest of the pool bathing suits were required. And I was as comfortable in both areas. I don’t even remember looking at men. Because they were just bodies without clothes on. Nothing weird about that. What was weird was the occasional person who tried to use the sauna and ‘cooling off’ pools in their bathing suits. They wanted to sweat into their suits? Eww, gross.
I had sleep overs with one friend whose parents slept in the nude, walked around in the morning nude and left the doors open when they used the bathroom. I had sleep overs with an other friend whose parents I never even saw in a nightgown. Both were just…parents.
Maybe that my parents and a lot of my friends parents were old hippies had something to do with that.