There's a philosophical question in the fact that something just became more treasured because of DNA testing results, but I'm not even going to attempt answering that.
W.F. Lloyd, 1833, "A Lecture on the Notion of Value as Distinguished Not Only from Utility, but also from Value in Exchange".
http://socserv2.socsci.mcmaster.ca/~econ/ugcm/3ll3/lloyd/val...