Political Orientation and the whole sheebang

This week’s reading for PIG-IE is

Kandler et al (2012). Left or Right? Sources of political orientation: The roles of genetic factors, cultural transmission, assortative mating, and personality.  Journal of Personality and Social Psychology, 102, 633-645.


Enjoy and leave a comment if you like.

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2 Responses to Political Orientation and the whole sheebang

  1. pigee says:

    Since the PIG-IE group is bashful, I’ll summarize the discussion and the questions that arose, and maybe the authors will provide a response.

    1. Some members of the group still question the model assumptions of twin designs. In particular, despite the twins-raised apart studies obviating this criticism, some folks still complain that the environments for MZ twins cannot be equivalent to the environments of DZ twins-at least not in a psychological sense. Some thoughts on this would be great.
    2. Some of the other assumptions appear untenable–absence of nonadditive effects, no gene-environment correlations, etc. It would be nice to know what happens if these assumptions were to be relaxed.
    3. Some members of the group could not fathom that political orientation is the same thing in Germany as it is in other countries and therefore asked how the results could be interpreted. This, in part, is a question about the construct being measured and whether a more specific measure would lead to different estimates and whether the measure is truly comparable across countries.
    4. One implication of the study is that personality traits are causally prior to attitudes. One wonders if this is a correct inference. Some attitude researchers feel ambivalent (at best) toward variables like personality traits (feel they are poorly specified and unimportant). Their skepticism leads to a chaffing at the finding that political attitudes are genetic and that a large chunk of what is genetic is attributable to personality traits. How would you respond?
    5. What the heck is going on with acceptance of inequality? The findings for that dimension are qualitatively different. Why?
    6. The model and structure were very complex. One thing that escaped me (Brent) is how you could differentiate between allelic dominance and epistatic effects. It would be great if someone could explain that so that those of us how are cognitively challenged could understand it better.
    7. People still have a hard time wrapping their head around the idea that shared environments are not more important.

    • Christian Kandler says:

      1.There are now a lot of good studies which have shown that the equal environment assumption does hold, at least for MZ and DZ twins and at least for personality.

      2.For complex traits, the assumption of additive genetic contributions is robust even if there are large contributions of nonadditive genetic effects or gene-environment interplay. That is, possible nonadditive contributions and gene-environment interplay are confounded with estimates of additive genetic effects. Thus, estimates of additive genetic effects are good estimates of overall genetic involvement (linked or not linked to environmental contributions) including nonadditive genetic effects.

      3.This, in fact, is right. Even though across many eastern and western countries the two factors “acceptance of inequality” and “resistance to change” were found, further research is needed.

      4. Yes, it’s an assumption. However, meanwhile some researchers have tested the directedness.
      for an overview.

      5. I have no answer. We need further research!!!

      6.Because of different shared effects between specific dyads:
      Additive (A) Allelic dominance (D) Epistasis (I)
      Parents-child 0,5 0,0 0,0
      MZ twins 1,0 1,0 1,0
      DZ twins 0,5 0,25 0,0
      However, the estimate of nonadditive genetic effects due to allelic dominance in our model was confounded with contributions of twin-specific environmental effects. Therefore, estimates of epistatic effects were more robust accounting for the fact that MZ twins are more as twice as similar than DZ twins or parent-child dyads.

      7. Yes, I can understand this, but we should note that objectively shared environment, such as familial environment, is not necessarily shared by the offsping but may be effectively not shared.

      All the best,

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