Nah, the Romulans were some offshoot of the Vulcans. & we all know how rational the Vulcans are/will be (damn temporal mechanics. Never a good one around when you need one.)
Somehow the Romulans got sidetracked into a warrior society - like hyped-up samurai. You'd think that with a bedrock faith in rationality, that the proto-Romulans would have been fairly immune to false premises, but something happened to them along the way. I don't recall - or more likely, Roddenberry never explained - what sent the Romulans down the societal path they took.