Sister
I caught my sister masturbating when we were in high school. I never told anyone including her and I had snuck into her room and found her little toy. We were adults with kids of our own and she was in town visiting and staying with me. We got on the subject of sex, because I was single she asked me what I did and I told her I mostly got myself off. She commented about how she didn't do that because it didn't do anything for her, I started to let it go but before I knew it I was telling her I had seen her. She said, you ain't never saw me doing that and I told her yeah I did and I know where you kept your toy. She said I didn't have no toy, me and "insert our brothers name" use to fuck, what I need a toy for? I almost fell over, she was here admitting she had sex with our brother but still denying she masturbates, unreal.
My sis and I shared a room like most sibs do. She was the one that taught me about masturbation when I was about nine years old. She admitted doing it since learning about it from attending sleepovers with her older circle of friends. We never ever engaged in any lesbian activities but we did occasionally both masturbated in our separate beds at the same time.
I was the one that brought and initiated the idea to masturbate during sleepovers with my circle of friends. We eventually did engage in lesbian activities as we gained trust in each other. As and adult I identify as Bi but have not come out to my family or friends outside my occasional female lover.