Are your older siblings smarter than you? Blame your parents, study says

Oldest siblings tend to earn better wages and receive more education than other children of the family, previous studies have found. A new study has something else the eldest can brag about: higher IQs.

The study, by researchers at the University of Edinburgh, also tried to explain why that happens. Apparently, parents tend to give more mental stimulation to their first-born children than they do to the others, and that has long-term effects.

Researchers studied data collected by the U.S. Bureau of Labor Statistics about 5,000 children from pre-birth to age 14, which assessed the kids every two years. The children took tests, including matching letters, naming names, reading single words aloud and completing picture vocabulary assessments. Parents were surveyed on their actions, including pre-birth behavior, such as smoking and drinking activity during pregnancy, and post-birth behavior, such as mental stimulation and emotional support.

The findings showed first-born children tended to score higher on verbal, reading, math and comprehension skills as early as just after birth to age 3, and differences in performance between first-borns and other children increased with age.

That’s more due to nurture than nature, according to the study.

“Researchers found that parents changed their behavior as subsequent children were born,” the summary continued. “They offered less mental stimulation to younger siblings also took part in fewer activities such as such as reading with the child, crafts and playing musical instruments.”

Mothers also tended to take more risks during the pregnancies of latter children, including smoking.

“Our results suggest that broad shifts in parental behavior are a plausible explanation for the observed birth order differences in education and labor market outcomes,” said Dr. Ana Nuevo-Chiquero, of Edinburgh University’s school of economics.

First-borns tend to rack up a lot of advantages, according to a survey by Career Builder. Compared to their siblings, they’re more likely to earn $100,000 or more annually, pursue careers that require higher levels of education and hold senior management positions.

This story was originally published February 9, 2017 at 1:31 PM with the headline "Are your older siblings smarter than you? Blame your parents, study says."