Firstborns have higher IQs than their siblings

Firstborn babies have a higher IQ than their siblings

July 4, 2007 at 1:45 am

This short article from Science reports tasty discoveries about the relationship between birth order and intelligence. While it is generally accepted in the scientific community that older siblings generally have higher IQs due to various environmental influences, numerous possible factors make it difficult to demonstrate causality from a correlation. One criticism is that later siblings are likely to come from larger families, which is related to lower socioeconomic status and IQ.

A study with 241,310 Norwegians shows that it is the social order of the siblings rather than biological factors that causes the different intelligences in siblings. This study supports the popular confluence theory, which claims that intelligence is directly influenced by the intelligence level of other family members. Older siblings benefit from the extra time spent with their parents, while younger siblings are negatively influenced by the other children.

In nature vs. care, nourish takes this round.

Kristensen, P. & Bjerkedal, T. (2007). Explain the relationship between birth order and intelligence. science, 316 (5832), 1717. [PDF]

Entry filed under: Birth order, intelligence, relationships.

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