I've compiled all of the reported catnip studies and run some large-scale surveys of my own: https://www.gwern.net/Catnip https://www.gwern.net/Catnip https://w

I've compiled all of the reported catnip studies and run some large-scale surveys of my own: https://www.gwern.net/Catnip https://www.gwern.net/Catnip https://www.gwern.net/Catnip-survey https://www.gwern.net/Catnip-survey Globally, catnip immunity rates are closer to a third, but Australia is at the extreme with about half cats not responding. Villani 2011 https://www.gwern.net/docs/catnip/2011-villani.pdf https://www.gwern.net/docs/catnip/2011-villani.pdf establishes that catnip response is highly heritable but polygenic (not Mendelian), and to a first approximation, no one studies cat genetics - so it will be difficult to prove that there's some sort of founder effect on Australian/Mexican/Spanish cats causing a lower genetic propensity.