The Sibling Effect

A study finds that males with elder sisters are less competitive than those without

Our personalities and psychologies are shaped by several things. But can something like the sex of our sibling or the order of our birth in the family also have a significant impact?

A new study—conducted by researchers from Okayama University in Japan and published in British Psychological Society’s Research Digest—has found that these two factors do have a role to play. Boys with elder sisters are less competitive than those without elder sisters, they claim.

For the study, a total of 135 high school students participated in an initial experiment, and 232 university students participated in a follow -up. The students were asked to choose between two types of game to play. The first game was a ‘piece-rate payment system’ in which individuals gather modest points for each correct answer. In the second game, a ‘tournament system’, a much larger reward was made available but only if the students beat those who had been assigned to their group. In a later trial, the participants were allowed to choose which system they would prefer to participate in.

The researchers discovered that secondary-school boys were much more likely to choose the competitive option than girls, with 61 per cent opting for the tournament. But when only boys with elder sisters were considered, that number dropped to 38 per cent. Among the university students, men were more competitive than women, but men with an elder sister were 21 per cent less likely to choose the tournament than those without. However, women with elder sisters were more competitive— bringing their willingness to take part in the tournament challenge in line with the male average.

According to the researchers, the reason that males with elder sisters tend to be less competitive in comparison with their peers could be what they term ‘role assimilation’. They claim that children may be absorbing some of the gender- stereotypical traits of their siblings. Also, the eldest child is often found to be under more pressure to meet parental expectations, suggest the researchers, leading later-borns to be less competitive.

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