People with children live longer, study finds — but only this many kids

Having a tot or two can increase your lifespan — no kidding. 

Selfishly reveling in the child-free lifestyle has newly become all the rage among footloose millennial couples — better known as “DINKS,” an acronym for Double Income No Kids — who’d prefer changing time zones by traveling the world rather than changing rank diapers.

However, a December 2023 study from the University of Michigan suggests that parenting children can actually extend a person’s life expectancy to age 76.   

“One thing that is relatively clear is that having children is more beneficial to longevity than not having children at all,” research author Jianzhi Zhang said. 

For the findings, he and co-author Erping Long, a student of the Chinese Academy of Medical Sciences and Peking Union Medical College, reviewed the health and genetic information of 276,000 individuals living in the United Kingdom.

They determined that men and women with small broods boast a higher probability of living long enough to see their little ones grow up. 

“Having two kids corresponds to the longest lifespan,” he added, in part, noting that folks who become parents have a 5% to 10% longevity advantage over childless people.  

“Having fewer or more kids both lower the lifespan,” said Zhang. 

He partially credited the likelihood of a longer life with the built-in benefits that come with raising tykes. 

“Previous studies found that people with children tend to have more social interactions, such as interactions with other parents and teachers, and higher social contact is known to be linked to longer life,” Zhang explained. 

“It is possible that having two children strikes a balance between having a good amount of social interactions and not having too much economic or physical burden.” 

And his life-extending parenting hack might be right on track. 

A 2017 report also discovered that children aid in keeping their moms’ and dads’ minds active in old age — adding a whopping two years to their lives. 

A 2020 probe posited that women who give birth to babies later in life have a greater chance of living longer due to increased genetic material known as “leukocyte telomeres,” which imply good health and reduced risk of chronic conditions such as Type 2 diabetes, cancers and cardiovascular disease.

Per his study, Zhang, too, maintained that reproduction and lifespan are affected by both genes and one’s environment. 

His research supports the 1957 findings of evolutionary biologist George Williams. The decades-old theory — now known as the antagonistic pleiotropy theory of aging — proposed that genetic mutations that contribute to aging could be favored by natural selection if they are advantageous early in life in promoting earlier reproduction or the production of more offspring. 

But Zhang determined that reproduction and lifespan are genetically strongly negatively correlated, meaning that genetic mutations that promote reproduction tend to shorten lifespan.

The research team also found that individuals carrying mutations that predispose them to relatively high reproductive rates — people who are genetically inclined to have a lot of kids —  have lower probabilities of living to age 76.

Conversely, folks carrying mutations that predispose them to relatively low reproductive rates are expected to live well into their golden years. 

However, compared to environmental factors — such as contraception, medical advances, access to online resources and abortion — genetic factors play a very minor role.

Zhang noted that human life expectancy, birth rate and reproductive behavior have all changed drastically over the last few decades. Although worldwide birth rates have declined since the 1950s, life expectancy has steadily increased from 46.5 years in 1950 to 72.8 years in 2019. 

“These trends are primarily driven by substantial environmental shifts, including changes in lifestyles and technologies, and are opposite to the changes caused by natural selection of the genetic variants identified in this study,” said Zhang.

“This contrast indicates that,” he continued, “compared with environmental factors, genetic factors play a minor role in the human phenotypic changes studied here.”