As an historian (I'm sorry, I know that sounds pretentious), I have come to believe that Wrong is Wrong no matter what your culture and historical period tell you. The best example is slavery in America. From a modern standpoint, few would argue that slavery is wrong. Yet at the time, it was commonplace and socially acceptable, even respected by many. Still, that doesn't make it right - and a clear indication that it was very, very wrong is that it ended. Enough people spoke up and opposed it that, eventually, finally, and at great cost, it was finally put to rest.
Sure, there are things going on today that are wrong. And those things, too, will end - eventually, finally, and probably at great cost. They are wrongs in other cultures and wrongs in American culture, and this is where relativism blinds us - not into falsely believing that past rights were wrongs, but into thinking that modern wrongs are right simply because we are among the perpetrators. And we won't know how wrong they were until they are eradicated, and our grandchildren look at us and shake their heads and judge our misdeeds.
The key, then, is to take the past very seriously; the present, less so.