Genetics and Epigenetics in Families

The Genetics and Epigenetics in Families (GenFam) project utilizes a novel approach by combining genomic data with family-based sampling to study how genes and environments jointly shape epigenetic variation, behavior, and health.
 

Genetic tests have become increasingly popular: Millions of people now have their DNA analyzed—whether to learn about their geographical origins, possible ancestors, or genetically influenced health risks. The results often seem to promise insights into one’s body, psyche, or future disease risks. In reality, these individual predictions are noisy, nondeterministic genetic correlates. Whether and how genetic predispositions unfold over a person’s life depends on environmental conditions—family relationships, educational opportunities, social surroundings, and broader historical contexts.

It is precisely this interaction between genetics and environment that interests developmental psychologist Laurel Raffington. She leads the Max Planck Research Group Biosocial | Biology, Social Inequality, and Development, which investigates how genetic predispositions and social living conditions jointly shape human development. "I view the traditional ‘nature versus nurture’ debate as outdated," says Raffington. "Human development arises from the interplay of both." A particular focus of her work is developing biological measures that allow this interplay to be studied empirically across the lifespan.

Against this background, Raffington's GenFam (Genetics and Epigenetics in Families) project integrates genomic data into family-based research designs. These designs jointly analyze genetic information from parents, siblings, and, in some cases, multiple generations, allowing researchers to study individual differences within real family contexts.

GenFam builds on the German Socio-Economic Panel (SOEP), a nationwide longitudinal study that has surveyed thousands of households on education, income, personality, health, and living conditions since the 1980s. By drawing on these long-standing participant cohorts and supplementing them with biological data, Raffington’s research group can link social living conditions with genetic and epigenetic information.

To this end, households already participating in the SOEP study "Leben in Deutschland" are invited to provide additional saliva samples (see below). From these samples, researchers can analyze chemical modifications of DNA called DNA methylation. Because these markers respond to environmental factors, they show how these influences become biologically embedded over time.
 

SALIVA SAMPLING ALLOWS NEW RESEARCH OPPORTUNITIES
Blood is considered the gold-standard peripheral tissue for quantifying epigenetic processes. However, saliva samples are becoming increasingly important for research because unlike blood samples, they can be collected easily and painlessly at home and returned by mail. This significantly reduces costs and increases participation rates, especially in large population studies or when working with children. Saliva samples provide a wealth of biological information: they can be used to analyze genetic variants and epigenetic markers such as DNA methylation. These markers offer insights into how genes are regulated in the body and how environmental factors—such as stress or air pollution—influence biological processes. Studies show that epigenetic signatures derived from saliva samples are closely associated with health indicators like body mass index and are sensitive to social living conditions. Investigations by the Max Planck Research Group Biosocial have demonstrated that epigenetic data obtained from saliva samples can be used to generate valid measures of biological aging and related traits.

 

"DNA itself does not change over the course of life," explains Raffington. "But the relationship between DNA and human development is contingent on environmental and developmental mechanisms."

These epigenetic processes also help explain why social conditions matter for health. Raffington's research has linked differences in epigenetic patterns to social dimensions of "health," such as poverty and experiences of racism. She has also observed similarities in epigenetic profiles between mothers and children. However, because parents and children share both genes and environments, without genetic data it remains unclear whether such family resemblance reflects social influences, biological inheritance, or both.

This is where family-based genomic designs excel. By including data from multiple relatives, researchers can better disentangle genetic from environmental effects. Siblings provide a natural experiment: they typically grow up in the same household but possess random genetic variations. Leveraging these differences enables a more precise understanding of trait development and the specific environmental factors that moderate genetic expression.

Family genomic data also make it possible to study parenting without genetic confounding. "Genetic nurture" refers to the idea that parents' genetic traits can influence their children's development indirectly—through the family environments that parents create—even when the relevant genetic variants are not passed on to the child. By accounting for both transmitted and non-transmitted parental genetic variants, researchers can estimate these indirect pathways. This approach enables researchers to examine how genetic variations within families relate to distinct environmental experiences and interact with broader structural contexts, such as school tracks or birth cohorts.

Between March and October 2027, around 40,000 individuals are expected to be invited to participate, with an anticipated participation rate of approximately 60%. Both genetic and epigenetic data will be collected from as many participants as possible, laying the groundwork for one of the largest (epi-)genetic family studies worldwide.