Keine Beweise für den Einfluss des Geschlechts der Geschwister auf die Persönlichkeit in neun Ländern

Eine interessante Studie hat untersucht, wie sich ein andersgeschlechtlicher Geschwisterteil auf die Persönlichkeit auswirkt:

Does growing up with a sister rather than a brother affect personality? In this article, we provide a comprehensive analysis of the effects of siblings’ gender on adults’ personality, using data from 85,887 people from 12 large representative surveys covering nine countries (United States, United Kingdom, The Netherlands, Germany, Switzerland, Australia, Mexico, China, and Indonesia). We investigated the personality traits of risk tolerance, trust, patience, locus of control, and the Big Five. We found no meaningful causal effects of the gender of the next younger sibling and no associations with the gender of the next older sibling. Given the high statistical power and consistent results in the overall sample and relevant subsamples, our results suggest that siblings’ gender does not systematically affect personality.

Quelle: No Evidence That Siblings’ Gender Affects Personality Across Nine Countries

Das ist ja eine durchaus interessante Frage: Sind zB Jungs mit einer großen Schwester etwas weiblicher, weil sie sich dort etwas abgucken? Oder umgekehrt ein Mädchen mit einem großen Bruder „härter“ oder eher eine Art „Tomyboy“?

Anscheinend nicht nach dieser Studie. Aber zunächst zu den Grundlagen:

Two theories make opposing predictions about the causal effects of siblings’ gender on personality. The theory of social learning states that siblings learn from each other and assimilate to each other through social interactions (e.g., Brim, 1958). Thus, having a sister would lead to more feminine characteristics; having a brother would lead to more masculine characteristics. From this, it follows that children with an opposite-gender sibling will have fewer gender-stereotypical characteristics compared with those with a same-gender sibling.

In contrast, the theory of sibling differentiation states that, because of sibling rivalry, siblings will differentiate themselves in the process of developing their identities (Bossard & Boll, 1956). The differentiation process may also be driven by parental behavior; for example, fathers might spend more time with their sons and mothers more time with their daughters in households with children of both genders (Brenøe, 2022). According to the sibling-differentiation theory, having a sister reduces feminine characteristics, whereas having a brother reduces masculine characteristics. Consequently, children with an opposite-gender sibling should have more gender-stereotypical characteristics compared with those with a same-gender sibling.

Both theories have received some empirical support since the 1950s. Studies have found results supporting the social-learning theory, in particular in children (e.g., Brim, 1958; Okudaira et al., 2015; Stoneman et al., 1986; Sutton-Smith et al., 1964), but also supporting the sibling-differentiation theory in both children (e.g., Grotevant, 1978; Leventhal, 1970; Rodgers et al., 1998) and, more recently, in adults (Brenøe, 2022). In addition, multiple studies resulted in either mixed findings or not much support for either theory (e.g., Detlefsen et al., 2018; Endendijk et al., 2013; Lamke et al., 1980; McHale et al., 1999). The literature thus remains inconclusive.

Die Vorgehensweise:

To estimate the effect of siblings’ gender on personality, we searched for representative surveys that (a) would allow us to identify the respondents’ sibling gender composition, (b) included at least two of the personality measures we considered, and (c) had large sample sizes. On the basis of these criteria, we compiled a data set including data from 12 surveys (see Table 1). Our final sample consisted of 85,887 people; 55,203 of them have a younger sibling, 50,909 have an older sibling, and 20,225 have both. The survey respondents were on average 33 years old and 52% were female.

Also immerhin eine gewisse Studiengröße. Hiernach wurde gesucht_

We considered 10 personality dimensions: risk tolerance, trust, patience, the Big Five personality traits (openness to experience, conscientiousness, extraversion, agreeableness, neuroticism), locus of control, and a typical female personality (TFP) index. We generated the TFP index using five personality traits for which we observed systematic gender differences. Table S1 at https://osf.io/pmhfa/ shows the number of unique people for whom we observed each personality measure across surveys. We standardized the outcomes within each survey/year combination (M = 0, SD = 1).

Da sind interessante Sachen dabei.

Across all surveys, we found that the gender of the next younger sibling has no meaningful effects on women’s or men’s personality (risk tolerance, trust, patience, openness to experience, conscientiousness, extraversion, agreeableness, neuroticism, locus of control, and our TFP index; see Fig. 1). All point estimates were statistically insignificant and lay within a narrow range between −0.03 and 0.02 standard deviations. Furthermore, 95% confidence intervals (CIs) allowed us to rule out effect sizes larger than 0.08 standard deviations in absolute terms. The use of our combined measure of TFP allowed us to test the two competing theoretical predictions (social learning and sibling differentiation), and we were able to rule out effects larger than 0.04 standard deviations. For comparison, studies on birth-order effects on cognitive ability in Western countries have reported declines more than twice as large in magnitude from firstborns to children born later (e.g., Rohrer et al., 2015), and these effects are conventionally interpreted as small.

Fig. 1. Effect of having a next younger sister (as opposed to a younger brother) on the older sibling’s personality, separately for male and female older siblings, in standard deviations. Error bars indicate 95% confidence intervals based on standard errors clustered at the individual level. For underlying regression estimates, see Table S7 at https://osf.io/pmhfa/. Exp. = experience; TFP = typical female personality.

Das sind in der Tat minimale Unterschiede, die nicht relevant sind.

und noch eine Grafik:

Auch hier nicht wirklich etwas interessantes.

Ich könnte mir interessante Folgestudien vorstellen, die etwa untersuchen, wie viel die beiden Kinder miteinander zu tun hatten etc. Aber warum gerade geschlechtliches Verhalten groß abfärben sollte wäre auch nicht unbedingt ersichtlich. Denn es hat ja in vielen Bereichen einen stark biologischen Unterbau.

Als jemand, der mit einer älteren Schwester aufgewachsen ist, würde ich sagen, dass wir eben auch schnell viele verschiedene Interessen hatten, ich hatte mein Playmobil und auch einiges aus der „Masters of the universe“ Reihe, mit der sie wenig anfangen konnte und sie eben Barbies und andere Sachen. Und natürlich hatten wir auch Freunde, mit denen wir dann entsprechende Sachen gespielt haben. Was uns nicht abhielt bestimmte Sachen, wie etwa Sandburgen im Urlaub zu bauen dann eben auch gemeinsam zu machen.