Well, last year , when DD was in Reception, I heard from a friend who has a son then in Y1 that boys in Y1 were showing their parts to girls and that there was this "show me yours" culture. A week later DD told me that a group of boys and girls from Y1 pulled her knickers down to see her bottom. I took this incident in context of this "show me yours". I reported it to the reception teacher stressing that I find this unacceptable. She looked taking it very seriously. She investigated and told that there was inappropriate "sillinesss" going on in Y1 and the school dealt with it. Indeed they had some discussions with parents and lessons in Y1 to put this "silliness" under control, although I don't exactly know what. That was last year. I kept asking DD about anyone looking at her bottom and she didn't report anything until last week.
This year, I personally observed almost every day after school how Y2 girls and boy tease each-other that "boyfriends" should kiss "girlfriends" and I even heard words like "make love" , or was it "have sex"? I rejected this as a hallucination, I suppose. I was uncomfortable with this discourse of some children, in this years Y2 for a while. I don't know how Y1-Y2 children get to know those things.
Before I heard about the finger incident, I spoke with a number of mums from Y2 at a social gathering. They were aware apparently of the obsession with kissing, looking at bottoms and of the language used. They dismissed it as children didn't understand any of it in their opinion. They told me there was "boyfriend" culture, where boys were competing to have "girlfriends", some more than one, and if a boy kissed a girl's hand it meant they were "engaged". One mother told me my DD had a boyfriend and her body language as she was saying that made me uncomfortable. Other parents speculated how innocent older year groups were. The general mood was that it was all innocent and cute.
In my view this early sexualisation would make them explore things they don't need to and can't put in proper context at their age. There is also peer pressure to participate in this.
This was before the finger incident, which puts it all in a different light.
My DD told me the detail about the incident in several installments as it were. So I agree that maybe other girls didn't tell their parents all the detail. Or maybe the parents just are in denial, like I was, and minimize this as mere cute silliness.
I certainly view this as a culture of sexual assault and group bullying, an inappropriate sexualisation that clearly gone beyond anything innocent. One wonders how a 5-7 years old get to know about fingers.