Sibling rivalries are as old as society itself. Now, based on new research, it seems that siblings will have one more thing to argue about: who is smarter. It’s a common trope in TV and movies that the elder sibling is usually wiser and smarter than their younger siblings. It seems like that stereotype may actually be true.
According to a new study, the oldest born child tends to be the smartest of a group of siblings and have the highest IQ.
“We were surprised by the finding that birth order differences in cognitive test scores and parental behavior appeared so early,” co-author Jee-Yeon K. Lehmann, an economist at the Analysis Group in Boston, told TODAY.
“First-time parents tend to want to do everything right and generally have a greater awareness of their interactions with and investments in the firstborn,” Lehmann said. “With each subsequent child, parents tend to relax to a greater extent what they might deem as non-essential needs for their kids.”
This makes sense. According to CNBC, who also reported on the study:
Once parents have successfully brought one child into the world, they find it more challenging to devote the same level of time and investment to subsequent children. The research found, for instance, that parents spend less time reading to their younger children as well as teaching them basic concepts, such as the alphabet. Later-born kids were also less likely to be given mentally engaging activities or toys.
This shift in parenting had no impact on a child’s attitude or personality, but it did lead to increased academic confidence and performance for firstborns, according to the research, which is based on an analysis of data collected in the National Longitudinal Survey of Youth.
“The lesson here for parents is that the types of investments that you make in your kids matter a lot, especially those that you make in the children’s first few years of life,” Lehmann said.
“All those learning activities that you did with your first child as excited, nervous and over-zealous parents actually seem to have some positive, long-lasting impact on their development.”
The study also found that expectant mothers were more likely to take better care of themselves during their first pregnancy, avoid alcohol, and breastfeed their baby than they were with subsequent pregnancies.
This isn’t the first study to examine the impact of birth order on the life of children. Prior studies have found that the oldest sibling generally makes more money and have higher IQs. Subsequent siblings were more likely be have committed a crime, become pregnant as a teenager, and less likely to graduate from school.