Girls, Is it normal for sisters to do this?

My sister and I use to wrestle and fight a lot as kids. We don’t do it as much anymore but I went into her room and took her phone just to mess with her. She approached me on the couch and told me to give it back and started to try to wrestle it from me. She kept trying to take it from my hands but my grip is strong, so she slaps me in the nuts and I immediately let go. I was so shocked and in so much pain, but when I told me friend about it, she said it’s common for sisters to sometimes target their brothers there? Is that true?
Girls, Is it normal for sisters to do this?
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