The content of the novel gives no evidence that having any particular 'blood' had any particular value in dealing with the ring -- or, for that matter, for much of any other test of moral character. (I'm excluding Orcs and such.) If anything, the content of the novel suggests the complete opposite: it tends to set up comparisons between people of quite similar genetic and/or cultural background, and then show how they make very different decisions. Faramir/Boromir -- Various Bagginses -- and, if you go beyond the novels to the other books, an endless sequence of battling elves. The net conclusion seems to point to neither a genetic 'nature' nor a cultural 'nurture', but rather some sort of intrinsic moral character. Nature and nurture give the characters gifts, but then they choose the use of these gifts by intrinsic free will. For a small rhetorical flourish, c.g. Galadriel's gifts. For a completely out-of-universe theological comparison, consider the notion of a 'grace'.