It has a lot to do with it. Think about what you are saying. If a person is defined as your family, than you will help them more often. The issue there is making that stranger, be equal to your family. As much as you might think that's not possible, consider what happens when people marry, to see it happen all the time.
Familiar acceptance is similar to evil, in a sense that it's definition justifies action. The point of evil, is litteraly something that is as far from familiar as possible.