Your grandparents' education affects your biological age

Eating well, exercising and attending regular medical appointments can support a long and healthy life, but a new study has identified one possible factor beyond our control: whether you had a grandparent who went to university.

Studying data across three generations — education of parents and grandparents, and health data from parents and their children — researchers from Drexel University, the University of California and the University of North Carolina found a statistically significant association between grandparents’ education level and their grandchildren’s epigenetic-based ‘real’ age, which considers the age of cells and proteins linked to DNA in the body. Their results were published in the journal Social Science & Medicine.

“The research community has established a link between how social factors, socioeconomic factors and childhood adversity can contribute to health trajectories,” said lead author Agus Surachman, PhD, who completed his work on the study as a postdoctoral scholar at University of California, San Francisco. “We know from animal studies that health is transmitted across several generations, from grandparents to grandchildren. But we now have robust human data that shows that not only do parents’ socioeconomic factors play a role in their children’s health, but that influence goes back an extra generation as well.”

Previous human studies in this area found that exposure to traumatic experiences, such as the Holocaust and Tutsi genocide, can influence the methylation of genes among survivors and their children. The data in this study fills an important gap by examining a general population, and a common crude index of social stress exposures: level of education. The authors say parents’ education level is a useful metric for children’s early life socioeconomic status and exposure to social stressors.

Mothers were recruited to the NHLBI Growth and Health Study (NGHS 1) when they were 9–10 years old, and then re-recruited three decades later for the National Growth and Health Study (NGHS 2), to gather health and education information and the health information to determine their youngest child’s (ages 2–17) epigenetic aging, or biological age. The researchers controlled for other factors that may influence child health, such as age of the grandchildren, sex, children’s BMI and characteristics of the mother, including family structure, health profile and marital status.

The researchers found that the grandchildren of college-educated grandparents showed slower biological aging (ie, younger biological age relative to chronological age) than those whose grandparents did not graduate from college, based on five different epigenetic-based aging clocks. These clocks use a saliva swab to examine a biological process known as DNA methylation — which changes as the body ages — to predict an individual’s age based on their health profile at the cellular level.

The team also wanted to understand if the health of the mother might help explain the transmission effect between grandparent education and grandchild biological age. They used mother’s childhood and adult health data, measuring factors like BMI, cardiovascular health and adult c-reactive protein to measure body inflammation and found that the health of the mother explained a small amount of the link between grandparents’ education and epigenetic age of their grandchildren (14.5% to be exact).

“The link between a grandparent’s socioeconomic status and a grandchild’s epigenetic age is a remarkable finding, across generations,” said senior author Elissa Epel, a professor at the University of California, San Francisco. “This opens up a myriad of possible explanations and will need to be replicated. For now, we know that the mother’s poorer metabolic health is a partial mediator of this relationship.”

The study authors are following this cohort to examine grandparent and parent predictors of the offspring as they reach adulthood. They are also looking at social and psychological factors of accelerated epigenetic aging in samples with chronic conditions, including breast cancer survivors and chronic kidney disease. However, more research is needed to examine the myriad of factors that influence health trajectories of youth.

“In the United States, we tend to overemphasise individual responsibility when it comes to health — and there’s a lot of blaming people for their poor health,” Surachman said. “But the reality is that health is much more complex than that. Some factors are simply beyond our control, such as the genetics and the inherited epigenetics we are born with.

“This understanding about the intergenerational nature of transmission of social advantages and health should make us rethink our values.”

Image credit: iStock.com/Kobus Louw