I have a pet hypothesis that, on average, those into step porn are more likely not have grown up with a sibling of the gender they fancy. I reckon those of us who did are more likely to repelled by anything alluding to incest.
People who grew up with ACTUAL hot step siblings notwithstanding.
A man that brings me pizza, especially with extra sausage, may not automatically be my perfect partner but he’d be pretty up there.
Add a rug of chest hair I can wrap my fingers in…