- First-born children get more mental stimulation during early years
- Older siblings get better wages and more education in later life as a result
- Mothers also took ‘higher risks’ during the pregnancy of latter-born children
First-born children are smarter than their younger siblings, according to new research.
Economists at the University of Edinburgh have waded into the age-old debate and concluded that first-borns have a higher IQ test score than their siblings as early as age one.
Researchers said the findings could be explained by first-born children receiving more mental stimulation and support in developing thinking skills from their parents during their early years.
Economists at the University of Edinburgh have concluded that first-borns have a higher IQ test score than their siblings as early as age one (stock image)
The findings, published in the Journal of Human Resources, could help explain the so-called birth order effect when older siblings in a family enjoy better wages and more education in later life, according to researchers.
The study, conducted in partnership with Analysis Group and the University of Sydney, examined data from the US Children of the National Longitudinal Survey of Youth collected by the US Bureau of Labour Statistics.
Almost 5,000 children were observed from pre-birth to 14 years old on their family background and economic conditions.
Every two years they were assessed on skills including reading and picture vocabulary.
The tests included reading recognition, such as matching letters, naming names and reading single words aloud.
Researchers applied statistical methods to the economic data to analyse how parental behaviour such as smoking and drinking during pregnancy was related to their child’s test score.
It was found that mothers took ‘higher risks’ during the pregnancy of latter-born children.
The findings, published in the Journal of Human Resources, could help explain the so-called birth order effect when older siblings in a family enjoy better wages and more education in later life (stock image)
Parents also offered less mental stimulation to younger siblings and took part in fewer activities such as reading, crafts and playing musical instruments.
The findings showed that advantages enjoyed by first born siblings start from just after birth to three years of age.
Parents changed their behaviour as subsequent children were born.
Dr Ana Nuevo-Chiquero, of the University of Edinburgh’s School of Economics, said: ‘Our results suggest that broad shifts in parental behaviour are a plausible explanation for the observed birth order differences in education and labour market outcomes.’
OLDEST SIBLINGS ARE MORE LIKELY TO BE OBESE, STUDY CLAIMS
Older sisters are more likely to be fatter than their younger sisters, a study has found
Younger sisters are more likely to be slimmer than firstborn girl, a study by Leipzig University found.
And the researchers warned that firstborns could be at risk of other health problems too.
The scientists looked at data on the health of 13,400 pairs of sisters and found that firstborn women were, on average, 29 per cent more likely to be overweight and 40 per cent more likely to be obese than second-born sisters.
The findings back up similar research on men that found firstborn males were more likely to be overweight than younger brothers.
The latest research examined data from pregnant Swedish women, gathered between 1991 and 2009. Weighed when they were between ten and 12 weeks pregnant, firstborn women were 1lb 4oz heavier on average than second-born sisters.
This meant their body mass index (BMI) was 2.4 per cent higher. Firstborn sisters were only negligibly taller, measuring an additional 1.2mm on average.
The researchers also noted a considerable increase in average weight over the 18-year period, rising by four ounces per year.
The experts, from the University of Auckland in New Zealand and Uppsala University in Sweden, said it was unclear why older sisters seemed to be heavier. But they said the findings could explain why obesity figures appear to be soaring.
Since families are shrinking, with fewer parents having more than two children, a greater proportion of people today are firstborns than in the past. So if firstborns are more likely to be overweight, that will push up obesity rates.
The scientists also said there is mounting evidence that firstborns are more at risk of health problems such as diabetes and high blood pressure in later life than their siblings. But the underlying causes for these differences are far from clear, they added.
Writing in the Journal of Epidemiology and Community Health, the team said: ‘Our study corroborates other large studies on men, as we showed firstborn women have greater BMI and are more likely to be overweight or obese than their second-born sisters.
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