The set theme was "relay".
We have read before about evolution and about what one man calls "the selfish gene" - the bizarre process by which characteristics are transferred and retained over countless millenia, though their original owners are long since dead. The relayance of characteristics, from one generation onto the next, has long been known in any case.
"He has your eyes"
"Her mother's bearing"
"We will breed from this rose, it has a most vibrant hue".
Sometimes the baton is dropped, and usually that's a disaster. Race over. Team Mutant DNF.