S.H.
My kids are 4 and 8. Boy and girl.
I and my Husband change in front of them... not making it a big deal... it just is. We don't flaunt anything, we just change clothes. They do too.
No biggie.
My kids don't think it is a big deal either.
When my oldest, my daughter, wants privacy, she just says so. Fine. We taught her that. And kids will do that, on their own at a certain age.
My kids will say "you have hair down there...." I say "Yes, that is what grown ups look like.. you will too when you grow up..." No biggie.
Both my kids know their body parts, that boys and girls look different. When I or my Husband are showering, they often barge right in and start talking about whatever. Its no 'shock' and no big deal to them. We don't act like its a big deal either. To my kids... its just not a big deal.
all the best,
Susan