Recognizing you're related to somebody does something. I propose that whatever it does increases empathy. And empathy might not be a categorically good thing, but it comes pretty close, at least until you extend it to all food groups. So maybe we could increase empathy among people by pointing out their relatedness. [emphasis mine]

I'm also not sure how generically good empathy is. I appreciate that you make the concession that it could be problematic. As any human emotion it can be driven to extremes. Therefore I see any use of that as potentially dark art. Use with care. It could get out of hand. Actually I think it already got out of hand with Animal Liberation and related social structures.