i am currently reading The Introvert Advantage: How to Thrive in an Extrovert World by Marti Olsen Laney, which was mentioned on Slashdot the other day. i've gotten to the section about the possible genetic basis for temperament, specifically regarding the difference between introversion and extroversion. Laney implicates the gene D4DR, i.e., the D4 subtype of the dopamine receptor, which has been tied to novelty-seeking behavior (which itself is highly associated with tendency to addiction.) I think that Laney has mistakenly equated novelty-seeking with extroversion, mostly because whenever i've taken the Meyers-Briggs personality test, i have consistently strongly scored as an introvert, and yet i totally have novelty-seeking behavior. but she also mentions serotonin, and i haven't reached that part of the discussion yet, so maybe i will end up eating my words.