European Journal of Personality, Eur. J. Pers. 25: 53–64 (2011)
Published online 20 July 2010 (wileyonlinelibrary.com) DOI: 10.1002/per.774

Gene Flow by Selective Emigration as a Possible Cause for Personality Differences
Between Small Islands and Mainland Populations

ANDREA CAMPERIO CIANI1* and CLAUDIO CAPILUPPI2

1Department of General Psychology, University of Padova, Padova, Italy
2Department of Psychology and Cultural Anthropology, University of Verona, Verona, Italy

      Abstract: Whether personality differences exist between populations is a controversial question. Even though such
      differences can be measured, it is still not clear whether they are due to individual phenotypic responses to the
      environment or whether they have a genetic influence. In a population survey we compared the personality traits of
      inhabitants of an Italian archipelago (the three Egadi islands; N ¼ 622) with those of the closest mainland population
      (Trapani area; N ¼ 106) and we found that personality differences between small populations can be detected.
      Islanders scored significantly lower on the personality traits of openness to experience and extraversion and higher on
      conscientiousness. We suggest that these personality trait differences could be an adaptive response to a confined
      socio-environmental niche, genetically produced by a strong, non-random gene flow in the last 20–25 generations,
      rather than the flexible response of islanders to environmental variables. To test this hypothesis, we compared subsets
      of the islander population classified by ancestry, birthplace, immigration and emigration and found that differences in
      extraversion can be accounted for by gene flow, while openness to experience and conscientiousness can also be
      accounted for by some gene–environment interactions. We propose a Personality Gene Flow hypothesis suggesting
      that, in small isolated communities, whenever there is strong, non-random emigration, paired with weak and random
      immigration, we can expect rapid genetic personality change within the population. Copyright # 2010 John Wiley &
      Sons, Ltd.

      Key words: personality traits; Big Five; Personality Gene Flow hypothesis; small islands

INTRODUCTION                                                           Denissen, & Miller, 2007a; Plomin & Crabbe, 2000; Plomin,
                                                                       Pedersen, Lichtenstein, & Mcclearn, 1994; Reiss, Neiderh-
Evidence for a genetic influence on personality reported in the         iser, Hetherington, & Plomin, 2000; Turkheimer, 2000).
scientific literature is often controversial (Crawford, 2007).          However, differences of opinion still exist as to how and
Recently, heritability researchers have started to converge on         why there is so much variability of personality within
an estimation of the genetic component in personality traits of        populations, and little convincing evidence has been found
between 30% and 60% (Benjamin, Li, Patterson, Greenberg,               of personality differences between populations that have
Murphy, & Hamer, 1996; Ebstein, Novick, Umansky, Priel,                different cultural and linguistic origins (Allik & McCrae,
Osher, & Blaine, 1996; Jang, Livesley, Angleitner, Riemann, &          2002; Allik & McCrae, 2004; Eysenck & Yanai, 1985).
Vernon, 2002; Turkheimer, D’Onofrio, Maes, & Eaves, 2005).             Terracciano, Abdel-Khalek, Adam, Adamovova, Ahn, and
Some studies have shown that specific genes are closely                 Ahn (2005), who analysed 3989 people from 49 different
associated with specific traits (Benjamin, Ebstein, & Bel-              cultures, found that the perception of personality character-
maker, 2002; Benjamin et al., 1996; Hansenne et al., 2002).            istics of one’s own and others’ cultures are based on
Despite growing evidence, these findings are still debated, as in       unfounded stereotypes that may serve the function of
the case of DRD4 (Ebstein, 2006). Personality traits, which            maintaining national identity (Robins, 2005; Terracciano
constitute a complex phenotype, are likely to be influenced by a        et al., 2005). Others suggest there is a resistance to
number of interacting genes (Eley, Dale, Bishop, Price, &              recognizing genetically influenced population differences
Plomin, 2001; Jang, McCrae, Angleitner, Riemann, &                     in behavioural traits. This has caused most people to regard
Livesley, 1998).                                                       admitting the existence of such differences as unacceptable
                                                                       (Crawford, 2007). Our position is that the possible genetic
    Many researchers highlight the role of gene–environment            influence on personality traits in populations constitutes an
interactions in the study of personality at an individual              interesting scientific discussion that should be approached
level (O’Connor, Caspi, DeFries, & Plomin, 2003; Penke,                with an open mind and a sound scientific approach. In order
                                                                       to assess personality differences between populations,
*Correspondence to: Andrea Camperio Ciani, Department of General       Camperio Ciani et al. (Camperio Ciani, Capiluppi, Veronese,
Psychology, University of Padova, Via Venezia 8, 35100 Padova, Italy.  & Sartori, 2007; Camperio Ciani, & Ceccarini, 2002) used a
E-mail: andrea.camperio@unipd.it
                                                                                                            Received 30 November 2009
Copyright # 2010 John Wiley & Sons, Ltd.                                         Revised 22 March 2010, Accepted 24 March 2010