Claims regarding the eldest children in a family being luckier and more intelligent than their siblings are no longer just folk wisdom. A report prepared for the National Bureau of Economic Research (NBER) by researchers from the United States, China, and Denmark has revealed the scientific foundations of the "firstborn phenomenon." Zamin.uz presents the findings of this intriguing study.
Microbes: An "unexpected" factor for success
Statistical data confirms that firstborn children typically stand out with higher IQ levels, better academic performance, and higher future earnings. However, the reason lies not in genetics, but in the environment. Scientists are referring to eldest children as unique "biological couriers."
The issue is that firstborns, who are the first to attend school or kindergarten, bring various infections home. This deals a serious blow to the health of younger siblings whose immune systems have not yet strengthened. For instance, observations conducted in Denmark showed that second-born children are 2–3 times more likely to be hospitalized with respiratory illnesses during their first year of life compared to firstborns.
In such situations, the younger child's body is forced to expend all its energy fighting infection and inflammation rather than developing the brain. According to researchers, this "microbe factor" explains nearly half of the future income gap between siblings.
Parental attention and "productive hours"
The remaining half of the success is linked to parental behavior. According to time-use data from the United States, firstborn children receive 20–30 minutes more quality time (intellectual stimulation) per day than their younger siblings.
The reason for this is simple:
The first child "captures" the period when parental attention is at its peak, energy levels are high, and the child's brain is most ready to absorb information.
Younger children often "inherit" parents who are tired and spend most of their time attending only to the child's physical needs (feeding, cleanliness, and sleep).
Consequently, firstborns significantly outpace their younger siblings in the intellectual race during infancy.
Dear readers, is this situation observed in your family as well? Are eldest children truly more successful than their siblings?
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