Förstfödda egoister

Påverkas människors personlighet av födselordning? Den nya experimentella studien ”Birth Order Affects Behaviour in the Investment Game: Firstborns Are Less Trustful and Reciprocate Less”, publicerad i Animal Behaviour, antyder att så är fallet:

We tested the hypothesis that birth order can shape adult cooperative behaviours towards nonkin. An anonymous investment game was played by 510 unrelated students. The results of the game show that firstborns were less trustful and reciprocated less than others. No significant differences in trust or reciprocity were found among laterborn and only children based on birth order. Firstborn status was a better predictor of cooperativeness than age, sex, income or religion.

En av studiens upphovsmän spekulerar om en möjlig orsak till att förstfödda kan vara mer egoistiska:

One possibility, the researchers say, is family dynamics. When new siblings arrive, they siphon off parental attention, and in response firstborns feel the need to compete more and cooperate less. The behavior of children without siblings fits that explanation: They behaved like middle and lastborns. ”That suggests that what influences cooperative behavior isn’t being born first … but instead a child changes his behavior when another sibling arrives,” Courtiol says.

Om föräldrar är medvetna om denna möjliga effekt, kan de genom medvetna strategier påverka sina förstfödda att bli mer tillitsfulla och omtänksamma? Hur kan sådana strategier i så fall se ut?