ugh... I can't even begin to think of how complex that would be genetically. Someone should do brain scans of, say, N vs. S participants solving specialized tasks. Then we might get some significant differences and begin from there... The idea is to get this personality theory to manifest itself physiologically somehow and work our way down to genes. I can see it now: ENTP transgenic mouse models with wildtype controls, and Oberon Gene knockouts (in honor of Oberon who is an ENTP mouse). Scientists, fill in the detail, 'cause I'm going to bed... for real this time.