[choof]

not gonna touch on the sex but I will touch on the time travel aspect. if you do end up time traveling back to the past and have sex with yourself, regardless of the consequences, would this be in this universe or another universe? if you never had sex with older-arch when you were younger, then I will assume one of two things: either you will never have a chance to go back in time and fuck yourself in this universe (the reason for this doesn't really matter). OR you will have a chance to do so, but because you don't have this memory, you actually fucked yourself from a different universe. I believe this would be two consenting parties and would be legally fine.