1/7 to 1/14 is incredibly low for a race that had been in close proximity to another for over a hundred years. If there were no preference, or if there were a positive preference for interbreeding, you'd expect by that time nearly all descendants of the initial minority race to trace most of their ancestry back to the majority race. That 6/7 to 13/14 of the members of the race can trace back the vast majority of their heritage to the initial minority race is proof that not much interbreeding was taking place.