Following up on what you said though, Bowsac: This paper (linked) appears in its abstract to imply more than one gene. (I'm not suggesting they're accurately measuring anything to any degree.)

I can't see beyond the abstract to be more sure because of the paywall.

The paper:
https://www.nature.com/articles/nature13673

An article that references the paper (just interesting to read, though very likely misleading--aligns with the thread's Smithsonian article) :
https://www.bbc.com/news/science-environment-29213892