A major U.S. study published in Nature Human Behaviour has found that providing low-income mothers with a substantial monthly cash stipend during their child’s first four years slows the pace of biological aging in their children, as measured by epigenetic clocks. The Baby’s First Years project randomised 735 children and 777 mothers across four metropolitan areas, with households assigned to receive either $333 or $20 a month for the first four years of life, via debit cards with no spending restrictions.
Biological aging in this study was assessed through DNA methylation, a process whereby chemical tags attached to DNA influence gene expression without changing the sequence. Scientists use epigenetic clocks to estimate how quickly the body is aging, with DunedinPACE tracking overall pace, and Epigenetic-g aiming to gauge brain health and cognitive function from methylation patterns.
Growing up in poverty has long been linked with poorer health, accelerated aging and reduced cognitive function later in life. The researchers note the early years as a likely sensitive window when financial hardship could imprint on a child’s developing biology.
In the four-city trial, mothers were recruited soon after birth in hospitals and randomly assigned to the two cash groups. The unconditional cash gifts were delivered monthly for four years and could be spent in any way the families chose.
When children reached four, saliva samples were collected from both mothers and children. The researchers used these samples to calculate each participant’s DunedinPACE score and Epigenetic-g score. The analysis controlled for maternal age, education, race, pre-study household income, and infant birth weight, comparing higher cash with lower cash families.
Results showed that the higher cash group had a slower pace of biological aging in their children, with a lower DunedinPACE score than the low-cash group. The researchers found no corresponding and consistent improvement in Epigenetic-g scores. They also checked GrimAge and PhenoAge, but found no group differences on those measures.
Raffington, who leads the Max Planck Research Group Biosocial at the Max Planck Institute for Human Development in Berlin, said: “Our previous work, including a recent meta-analysis of 140 studies encompassing nearly 66,000 people across 23 countries, established a robust, global pattern: lower socioeconomic status is consistently linked to accelerated epigenetic aging.”
She emphasised that while the study used a rigorous randomised design, the practical takeaway is that reducing financial strain can alter a child’s biology, even if the effect is small. “In medicine and social science, small individual effects can compound into large societal benefits when scaled across a whole population,” she added, noting that poverty leaves a biological footprint and that direct financial support to families is a powerful public health intervention.
Yet the researchers found no clear evidence that the larger cash gifts benefited the children’s Epigenetic-g scores, and there were no differences for the mothers’ epigenetic measures. The authors suggested that while extra income eased financial pressures, it did not appear to modify adult environmental stressors like housing quality or food insecurity, which are typically linked with aging in adults.
Raffington said she was surprised that the epigenetic measures did not relate to BMI, cognitive tasks or mother-reported socioemotional behaviours in the children, a contrast with some prior work. She suggested that the young age of participants might partly explain the discrepancy, with clocks capturing early biological underpinnings that do not yet manifest as visible developmental differences.
Researchers caution that these clocks are population-level tools and not yet validated as individual clinical diagnostics. They also note that clocks were developed from blood samples in older adults and that applying them to saliva in four-year-olds introduces potential accuracy limitations; most genetic data used in clock development come from populations of European descent, underscoring the need for broader representation in this research.
Looking ahead, the team will continue following the families to see whether any epigenetic differences persist as children grow older and whether slower aging in early childhood translates into measurable health advantages later in life. Raffington also points to pregnancy as a possible earlier window for financial relief, referencing the Rx Kids programme in Flint, Michigan, which reported improved birth outcomes when cash support began in pregnancy.
She praised the scale and collaboration behind Baby’s First Years, describing it as a rare example of “team science” funded by a mix of grants and philanthropy and “the immense value of slow, careful science that requires some patience and long-term funding resources”.
Finally, the study, titled “Effects of a randomized controlled trial of unconditional cash transfers on epigenetic measures of ageing and cognition in children and mothers”, lists Laurel Raffington and a team of co-authors including Yayouk E. Willems, Jessica F. Sperber, Sepideh Zarandooz, Molly A. Costanzo, Daniel A. Notterman, Colter Mitchell, Elliot M. Tucker-Drob, Greg J. Duncan, Nathan A. Fox, Lisa A. Gennetian, Katherine A. Magnuson, Sonya V. Troller-Renfree, Hirokazu Yoshikawa, Elisabeth B. Binder, K. Paige Harden, and Kimberly G. Noble.
