First, although we have used the term "personality type", we should more appropriately say "character type". Indeed, we consider personality to be primarily the resultant of two entities: character type (traits N, P and A) and temperament. Human temperament in the pavlovian sense -- a measure of an individual's level of activity or excitability -- clearly also has a genetic basis. Although our analysis focuses mainly on the first entity, character type, we allow for many other "modifier genes" contributing to temperament. (Consider the analogy of a television set: the "channel selector" is character type, the "volume control" is temperament, and the conditions in the room that determine how well the picture is actually seen is environment.)
Second, as implied above, the individual's personality type is mediated by environmental conditions, the effects of which may be considered to be overlaid on the genetically determined structure. Nurture counts!
Third, there are many other secondary aspects that go into "personality", some of them depending on cognition (intelligence, thinking and learning).
Despite the fact that personality and behavior can be complex indeed, clearly any analysis of human behavior must first begin with the identification of an individual's genetic NPA character type.
this time to the select an url for the above
http://www.geocities.com/ResearchTriangle/Campus/4847/