me and my sis accidently

My sister and me had been going through puberty so we both had been growing pubic hair and I could get erections. 3 weeks ago my parents went up to London for the day and left my sister and me alone in our house from 6 in the morning to 7 at night. This is the story when me and my sister done it for the first time accidentally but it still felt good.

I woke up and I walked into my sister room and woke her up too. She said she was going to have a bath and I said to her “I will have one after when you have got out. I went and got some breakfast and after I had done that I went back upstairs to get ready from a bath. I undressed myself and then I wrapped a towel round me and I went into the bathroom cause I needed the toilet and then I was going to get into the bath. I walked in and I saw my sister in the bath nude, her boobs were quite big and she had some pubic hair but not a lot. My penis started to become erect.