Did anyone's boy friend ever cheat on them with his own sister or vice verse? my ex did... he and his brother were doing somethings with they sisters. his brother was 19 he was 13 and his sisters were 9 and 17 they have been doing that for 3 years... the 19 year old brother was F.*.k. ing the 9 year old and my ex was doing his older sister he said i could leak his shi... i asked a friend and they said i should. Im to nice to people and this time i don't wanna be nice... I HOPE YOUR HAPPY THAT YOU F.*.C. K.E. D. your 17 year old sister... and you got her pregnant i wonder when your mom is going to find out... BTW FREE POINTS :)