As one of the resident girls,
Among woman, nudity is weird. Teenage girls tend to be more self consious, especially when around each other unless they are with female family members or close friends.
Woman who've given birth tend to lose a lot of it, at least for awhile, especially if they've breast fed.
My boss, who was downright prudish for ever, rolled her eyes when I averted mine when she was breast feeding once. She pointed out that after giving birth, with pretty much everything on display, you really just stop giving a *expletive deleted*it.
My mom is practically a nudist in her home. Hell, the last time I was over there, she wanted to change out of her riding clothes, so she walked into the bedroom and started stripping while still talking to me. Chalk it up to just doesn't give a crap. As far as she's conserned, I came out of below, had breakfast, lunch and dinner up top for the first 9 months of my life and my very exisitance is the reason for the big belly (her stomach muscles never contracted back, and genetically, she wasn't slender in the first place)
Very few woman seem to be disinclined to be naked with other woman in a casual setting.
I will admit to being one of the few.