i'm not sure . its normal i guess but i don't think u should do anything with her

If she's your half sister, it means she shares one of your parents, so she is related. It is semi-normal that you are attracted to her and all that, but don't take that any farther. Because if you fuck a relative, your kids will have three eyes and four legs...

if shes your stepsister you are not related so bang her but if anyone found out it would cause a lot of trouble in the fam

It is normal, but it sure does suck, doesn't it buddy? like they say, just don't take it any further!

make her suck your cock

YES ITS NORMAL,TAKE OUT THE BIOLOGICAL EQUATION AND YOU HAVE NOTHING,REMOVE THE MORAL EQUATION AND YOU GET LAID.THE PHYSICAL IS TEMPORARY,THE EMOTIONAL TRAUMA CREATED BY YOU DECISION WILL LEAVE A GUILTY SCAR IN BOTH YOUR LIVES,WHEN THE GOOD TIMES COME AROUND SHARE WITH YOUR SIBLINGS ,LIKE PICNICS AND WEDDINGS OR GRADUATIONS YOU TWO WONT BE THERE IN SPIRIT ,BE REAL AND ADMIT TO YOUSELF ITS OK TO FEEL THINGS BUT YOU CANNOT ACT OUT SOME THINGS THAT DONT FEEL RIGHT,IN YOUR HEART,NORMAL TO FEEL,NOT NORMAL TO ACT.MANUP AND BE PROUD YOU HAVE A FAMILY WHO LOVES YOU.

Half sister? If it is half sister then u are related. but if you mean that ur mom/dad got togheter whit another person and that person had a daughter then it's fine. (depending on age)