Whether you were born first or second in your family may be linked to small differences in the risk of developing certain diseases. This conclusion emerges from a large study published in the journal Nature. This was reported by Qazaqyia.kz citing Kursiv Media.

Researchers from the University of Chicago and other scientific centers examined medical data from 5.1 million families raising more than 10.3 million children. They assessed the association between birth order and the risk of developing 569 diseases.

Data were available for 418 diseases, and for 150 of them, a statistical link was found with whether a person was the first or a subsequent child in the family.

To ensure the reliability of the results, the scientists used two methods. In one case, they compared first and second children from as similar families as possible, accounting for sex, year of birth, parental age, region of residence, and other factors. In the second, they compared biological siblings within the same family.

Firstborns were more often diagnosed with autism spectrum disorders, attention deficit hyperactivity disorder (ADHD), Tourette syndrome, food allergies, allergic rhinitis, acne, and some anxiety disorders.

In second children, researchers found a slightly higher risk of substance use disorders, gastritis and duodenitis, biliary tract diseases, migraine, and shingles.

The authors emphasize that the differences were small. They believe they may be explained by several factors.

First, younger children often encounter different bacteria and viruses earlier because they grow up around older siblings. It is known that we share some bacteria with everyone we live under the same roof with. This may gradually "train" the immune system and make it more resistant to certain infections.

Second, health may also be influenced by the fact that parents sometimes treat the first child more cautiously: they visit doctors more often, which leads to more frequent diagnoses.

Additionally, younger children often enter the "adult" environment earlier—for example, they start interacting with older children sooner due to contact with siblings.

However, none of these hypotheses have yet been confirmed.

Birth order itself does not determine whether a person will get sick in the future, and the study results are not suitable for predicting an individual's health.

Earlier, Kursiv wrote about a study on children's lies: should you worry that a child will grow up to be a criminal if they lie often?

If the article causes you anxiety, discuss it with an artificial psychologist.