Morals cant be universal. Without humans they wouldnt even exist at least not how we see them.
And what if through GM, usage of certain hormones or w/e we would be able to breed human species that wouldnt be capable of empathy, or wouldnt feel that mindlessly massacring people was wrong. Then it simply wouldnt be wrong.
Everything is relative. But in my mind we can still judge other cultures from our culture. We cant judge the people from other cultures behaving like their culture dictates however.