That is such a shame and I am sorry about your sister, Me and my sister used to do similar things together when we were young experimenting and exploring each other at every opportunity we got we became so close that people thought it was cute as we would often hold hands together giggle and play together like two close sisters do, But little did everyone know at night in our shared bedroom our nighties came off and we would play our favourite game of husband and wife we'd take turns on top of each other grinding away on each other we even kissed too like we had seen people do on t.v. pretending to be hero and heroine, We learned what made us feel good with our fingers then our mouths by the time we were 13 (yes we are twins) we were having full blown sex together and we have never stopped we did try boys but we couldn't enjoy it we just wanted each other all the time we were apart, We share a flat together now everyone knows us and thinks it's nice for twin sisters to flat share as we do but they don't know that at night we sleep in the same bed and have wonderful sex together.