Historical Trauma & Transgenerational Epigenetics

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Historical trauma is a cumulative effect that depicts not only the emotional, but also the biological effects of systematic oppression. This subjugation intensifies in communities who suffered cultural loss, displacement, and colonization. Previous studies provide a rationale for investigating epigenetic patterns in Native American populations using DNA from blood repositories, contingent on the expressed consent from each tribe. Recent research suggests the potential for collective stressors to leave measurable traces on the genome through epigenetic mechanisms such as DNA methylation, which influences health outcomes long after the occurrence of original trauma (Conching & Thayer, 2019). DNA methylation “silences” or deactivates gene expression through an epigenetic process where a methyl group attaches to cytosine bases in DNA in the CpG site, where DNA methylation primarily occurs. (Higashimoto et al., 2023). However, it does not alter the genetic code itself, rather this mechanism serves as a record of the environmental influence of stress or trauma on a molecular level. Once that occurs, it may regulate the genetic functionality of gene expression across generations (Švorcová, 2023). Stress imprints at the molecular level are associated with alterations in DNA methylation and gene expression, which can be transmitted across generations via epigenetic mechanisms (Bunshi et al., 2025). Brockie et al. (2013), highlighted how disproportionate exposure to adversity within Native American communities contributes to the persistent health disparities which echo why epigenetic alterations are so prevalent within marginalized groups. Even stress-response genes show heightened dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis, contributing to disparities in physical and psychiatric health (Brockie, 2013).

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Evidence from Human Studies

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Human studies from Heijmans et al. (2008) and Bieber et al. (2020) provide compelling evidence that extreme historical stress could leave lasting biological markers. These exposures are associated with DNA methylation increases in IGF2, FKBP5, and NR3C1, stress-regulation genes that have been studied across populations, allowing for cross-study comparisons of persistent epigenetic marks. The Dutch Famine study demonstrated how environmental stress can imprint long-lasting epigenetic differences. Prenatal exposure to famine is associated with persistent methylation changes in the IGF2 gene, specifically affecting the mother's gamete (Heijmans et al., 2008). Bieber et al. (2020) identify differential methylation of FKBP5 and NR3C1 genes in Holocaust survivors and subsequent generations, associated with maternal trauma and consistent with epigenetic inheritance. These findings reveal how early-life stress can leave molecular footprints. Collectively, the findings suggest that sustained trauma leaves measurable molecular imprints, shaping gene expression and creating cascading health effects that persist across generations. Findings from Dutch and Jewish studies allow for thorough exploration of whether analogous methylation patterns exist within Chickasaw populations, where historical colonization and cultural loss may have induced significant stress-related biological signatures.

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Mechanisms, Context, and Theoretical Bridge

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Epigenetic transmission is a non-genetic inheritance that allows environmental experiences to influence biology through chemical modifications like DNA methylation (Banushi et al., 2025). These processes are a form of biological plasticity (Švorcová, 2023). These modifications represent molecular adaptations observed in response to stressors, without altering the underlying DNA sequence. In trauma research, methylation of stress-related genes such as FKBP5, NR3C1, and IGF2 serves as a molecular record of stress exposure, associated with altered stress-response regulation across generations (Banushi et al., 2025). Admixture studies reveal how intermarriage as a result of colonization shaped Indigenous genetic and epigenetic variation. Jorden et al. (2019) and Mendoza-Rivilla et al. (2022) highlight that forced assimilation and genocide created a complex biological as well as societal pressure for specific genes. These effects range from cultural pressures, such as altered skin pigmentation to blend in, to biological adaptations, like smallpox resistance in Native populations, which have been associated with long-term methylation changes observed across generations. Within Chickasaw populations, these admixture-driven shifts, as Native communities tried to survive, contributed to the effect of identity suppression and systemic trauma, resulting in specific epigenetic patterns in stress-related loci (Jordan, 2019). However, biocultural epigenetics is an emerging field that examines how social experience and molecular expression intersect (Banushi et al., 2025). Each significant stressor affects biological pathways, indicating that epigenetic modification reflects lived experiences or trauma, rather than a simple, black-and-white biological response. In Chickasaw populations, methylation of FKBP5, NR3C1, and IGF2 captures physiological stress as well as the biological legacy of oppression, consistent with potential transgenerational patterns of resilience. The process of bridging human biology with cultural history expands the DNA methylation alterations as not just biological but a historical marker designating how trauma and adaptation become intertwined across generations.​