@Basil Great response, and I must agree on most parts. Saving relatives obviously would go before any stranger, even if it's another race. However, let's say that there's a dog that you've owned for +5 years and a human stranger, then the human would be the obvious choice, right? So when choosing between a relative and a mutant stranger who's capable of saving many more humans during its 500 year long life (and who's also nicer, more sympathetic and caring on top of that), the option should, logically by morals, be to save the mutant. And even more obvious if both were strangers and it was a doctor who had to choose.
Basically, humans become animals at some point, in my opinion.