Ethics is objective, so if you want to defend preference for a particular group, you have to do so from the point of view of the universe. I think one could argue for an objective defense for some preference for family members, and preferences related to reciprocation, but it's very limited. But it is entirely irrelevant, and obviously so, whether or not you have 'never met' someone before. All interests deserve equal consideration no matter who has those interests - race, sex, nationality, culture, wealth, species - are all arbitrary.
There are many tough questions in ethics, not just in meta-ethics and normative ethics, but even in pragmatic or practical ethics. The refugee crisis, however, is not one of them. All you have to do is figure out what will have the largest net good. In this case, saving the lives of millions of people far outweighs the harms it may impose on the native population (the fact that they happen to be native, incidentally, is entirely irrelevant). In some cases these harms will be significant, but most of it will be minor. The interests it will satisfy in the people it helps are all rather crucial - primarily, the interest in continuing to live. This is not a difficult moral or utilitarian calculus.
I don't have much interest or care in preserving certain 'cultures' nor any traditions, but I don't ignore that it's an interest most people have and I don't deny that these interests should be taken seriously. Regardless, letting in as many refugees - with vetting to minimize harm - clearly results in the largest net good.