If you can keep it in the family, should you? I guess that depends on how taboo you like things. Speaking on a personal level I say give me and my cock as much family porn as you can and I will be a happy man. At Family Sinners almost nothing is off-limits.
I think it is fine to have options, without them life just doesn’t feel right. Fapnado just wants to offer you a helping hand with those options and you should take them up on the offer. Stop the real sin, the real sin has and always will be the one that is denying you of your true desires. If you want to bust a nut inside your step-sister’s pussy just go for it. You know she is just as desperate as you are for it, why else would she be walking in on you naked in the shower?