Everyone is curious - that is natural. And if it was just the one incident when she was 7 it wouldn't be much to talk about. But, she kept it up for 10 years.
Her parents were progressives who put up no boundaries and never told her "No" or that she'd done something wrong. That is why she can't understand the back-lash against her for what she did.
Up until our kids were about 3, my wife and I didn't worry much about them walking in on us when we were changing or in the bathroom. We certainly weren't trying to show off, but we weren't going to freak out and give them some kind of hang-up about their bodies. After that we taught them to knock, and we knock on their doors, taught them about modesty111c and respecting other people's privacy.
Morons like the Dunham's have no concept of those things.

The vagina photos maybe made her interested in vaginas?
I really feel sorry for her sister

I'm positive that if Lena thought she was molested, she would have used that as a way to gain more fame.
IF
the only thing she ever did was exploration when she was 7
AND
she talked about it as a cautionary tale to parents, then few would have issue with it. Everyone is curious at one point or another.
The problem was, their parents weren't good parents. Their father is a photographer and had pictures of their mother's vagina displayed at home.
Our lives don't have to end when we have children, but they do need to change. If an older child sees their mother nursing a baby it isn't horrific, but lock you porn away. Even something as tame as Playboy magazine still has erotic stories in them. Be responsible. Let your children have a childhood.
Their parents had to know something was going on, but being progressives they didn't care.