Waste of Space and Time.

Fucking is overrated, you can catch all sort of diseases and from there arise every problem, love, sex, fuck, it all got sorted out in the future, thus a code was injected to all time travellers, which when they travel back in time and go fuck themselves, then their reproduction system overheats and melts down, alongside with all the suppportive mechanisms of it, arteries, brain, heart and goes on.