Scientists have rubbished the theory that a child’s personality is influenced by the gender of their siblings.
Many think that children who grow up around multiple siblings of the opposite sex are influenced by them in terms of personality well into adulthood.
For example, girls with brothers are seen as likely to become ‘tomboys’, while boys with sisters are seen as likely to become ‘girlish’, according to common belief.
But a new study suggests this way of thinking is a misconception – and that sibling gender ‘does not systematically affect personality’.
Our personality as adults is not determined by whether we grow up with sisters or brothers, the new study claims. So girls with multiple brothers no more likely to grow up as ‘tomboys’ (file photo)
The new study was conducted by researchers from Leipzig University, the University of Zurich and Victoria University of Wellington, New Zealand and published in Psychological Science.
‘Our findings refute the idea that growing up with brothers or sisters causes us to develop certain personality traits in the long term that are considered “typically female” or “typically male” in a society,’ said study author Dr Julia Rohrer.
‘Overall, current research suggests that siblings have a surprisingly small impact on personality in adulthood.’
The researchers analysed data from more than 80,000 adults from nine countries, including the UK, the US, Germany, Australia, Mexico and China.
They used national longitudinal studies that systematically collect information about people over decades, including their living conditions, personality traits and sibling genders.
They investigated the following personality traits: trust, patience, ‘risk tolerance’ (the amount of risk they can take) and ‘locus of control’ (if they feel they have control over the outcome of events in their lives).
They also investigated the ‘big five’ personality traits – openness, conscientiousness, extraversion, agreeableness and neuroticism.
The ‘big five’ personality traits are the best accepted and most commonly used model of personality in academic psychology.
The ‘big five’ personality traits are the best accepted and most commonly used model of personality in academic psychology
In addition, the researchers looked at something called a typical female personality (TFP) index, which was generated using five personality traits for which they observed ‘systematic gender differences’.
Typically, female traits were lower risk tolerance, higher agreeableness and higher neuroticism, Dr Rohrer said.
Statistical analysis of this data showed across national borders that the personality traits are not systematically related to sibling gender.
They found ‘no meaningful causal effects of the gender of the next younger sibling and no associations with the gender of the next older sibling’.
Therefore, personality as adults is not determined by whether we grow up with sisters or brothers, they claim.
However, the results of the new study do not mean that sibling gender does not play a role at all in long-term life paths.
Across all surveys, researchers 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 the TFP index. Pictured, the effect of having a next younger sister (as opposed to a younger brother) on an older sibling’s personality
Economic studies have shown that in the US and Denmark, women with brothers earn less when employed.
‘So there do seem to be some interesting dynamics here that are related to gender, but personality is probably not part of the explanation for such effects,’ said Dr Rohrer.
Previous studies by Dr Rohrer and colleagues also show that sibling position – that is, whether a person is a firstborn, lastborn or a middle-born ‘sandwich child’ – also does not play a major role in personality.
Their 2015 study found who we become only marginally correlates with our birth position amongst siblings.
According to public perception, firstborns are supposedly perfectionists, while middle children develop a talent for diplomacy and last-borns are expected to be rebellious.