I'm really sorry! I got muddled up, I didn't mean to put sister in law I thought that was the one where your parent married someone else, but it isn't. I didn't mean to offend anyone, I'm really sorry.
Me and my step sister both are in love with each other (I'm a girl), we hangout out everyday as she lives with me. We've never done anything, but we aren't related by DNA... So it's not wrong? I don't know what to do, and it's not just a crush.
It's called having respect for her husband aka your brother so hands off! It's morally wrong. It is low and slimy if you continue on persuing this.
DNA has nothing to do with this .. Morally and ethically there is EVERYTHING wrong with it. You don't mess around with family .. Period !