Alright, here it goes. Every summer I visit my grandfather in Wisconsin. This year, my sister came also (she's actually my half sister and lives with her mom). Anyways, the house has two bedrooms and a foldout couch which I have a habit of building into so-called" forts, being large cave like buildings with a bed inside, and we were forced to share. I accidentally peeked at her changing on day, and...she was hot. (She is two years younger). Sometime into our visit, while sleeping, my foot touched hers, and I really don't know what happened, but what felt like a few minutes later, I was scrunched up behind her with my hand in her underwear massaging her vagina. She didn't wake up, as far as I can tell. I'm visiting again in July, and I want to know, should I do it again?