DNA and the Epigenome
Interactive 3D models · Genetics for mental health

DNA and the Epigenome

Four rotatable models. The first shows how the DNA double helix is built. The second shows how life experience adds chemical tags that switch genes on or off, and what that means for neurons. The third follows development from zygote to birth and shows how a mother's trauma can reach her child. The fourth traces chronic stress from slavery in America to children born today, and how counseling can change what comes next.

Model 1

The DNA double helix

Two sugar-phosphate backbones twist around each other. Paired bases hold them together on the inside: A always pairs with T, and C always pairs with G. Click any rung to inspect it.

Drag to rotate · scroll or pinch to zoom · click a base pair

Selected base pair

C–G

Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Backbone

B-form DNA by the numbers

2 nmhelix diameter
0.34 nmrise per base pair
10.5 bpper full turn
~3.1 billionbase pairs in the human genome
Model 2

Epigenetics: switching genes on and off

Epigenetics refers to chemical changes that turn genes on or off without changing the DNA sequence itself.

These changes are shaped by

  • Stress
  • Trauma
  • Nutrition
  • Environment
  • Parenting
  • Social conditions
  • Toxins
  • Exercise
Gene ONopen chromatin · euchromatin
DNA wraps around histone spools · change the factors to see the gene respond

Life experiences

Methyl tag (tends to silence) Acetyl tag (tends to open) Histone

What the gene state does to neurons

The DNA letters in this gene stay exactly the same in every setting: …ATG CGC GTA CCG… Only the tags change, and with them how much of the gene's product the neuron can make.

Brain imaging

Teaching simplification: this model uses one rule, where adverse exposures add methyl tags and pack chromatin tightly, and supportive ones add acetyl tags and loosen it. In real cells the direction depends on the gene, the tissue and the age at exposure, and some changes can reverse. Imaging findings describe group averages in research studies and are not used to diagnose an individual.

Model 3

From zygote to birth: how a mother's trauma can reach her child

Trauma can pass from mother to child along several routes: stress hormones crossing the placenta, epigenetic tags carried in the egg, inflammation, and coping behaviors such as substance use. Pick a stage to see what is forming and which conditions research links to maternal trauma at that point.

Embryoweeks 3–8 after conception
Amber dots: cortisol · grey dots: cortisol the placenta has neutralized

Stage of development

Mother's stress level

What is forming

Conditions linked to maternal trauma

Established cause shown directly Associated repeated links in human studies Emerging early or mixed findings
Keep in mind

Trauma raises risk; it does not decide the outcome, and it is never the mother's fault. Most children of mothers with trauma are born healthy. Treating maternal PTSD and depression, steady prenatal care, and social support during pregnancy all lower these risks, and nurturing care after birth can buffer many of the stress-system effects.

Model 4

From slavery to today: chronic stress across generations

Each column is one generation of parents, about 25 years apart, from people enslaved in America to children born today. The line across the tops carries stress forward from parent to child. On the right of the "Today" marker, choose a future: with or without counseling, and with or without changes to the conditions that keep producing stress.

Enslaved parentsbefore 1865
Click a column to read that generation · heights are an illustrative index, not measured data

Future scenario

Counseling and family support
Structural stressors

Selected generation

What parents lived through

What reached the children

Sources of strength

Four ways stress travels to the present

Biology in the womb

A mother's stress hormones and epigenetic tags affect her child and possibly grandchild. Evidence that tags alone persist across many human generations is weak. Black women born in Africa have preterm and low birth weight rates much closer to US-born white women than to US-born Black women, which points to conditions in the US rather than genes.

Family patterns

Parents under constant threat often parent for survival: strict, watchful, emotionally guarded. These habits protected children when danger was real. They can outlast the danger and pass on as family style.

Laws and systems

Sharecropping, Jim Crow, redlining, exclusion from wealth building and mass incarceration recreated stress in each new generation. Many researchers see this as the strongest link to today.

Sources of strength

Extended family, faith communities, Black colleges and institutions, and racial pride buffered stress in every generation. Good counseling builds on these strengths.

What counseling changes, and how fast

Weeks to months

Parent–child coaching such as Attachment and Biobehavioral Catch-up (10 home sessions) has brought young children's daily cortisol rhythm closer to normal.

1–2 years

Trauma-focused therapy (CPT, prolonged exposure, TF-CBT) reduces PTSD. In one small study of veterans, those who recovered showed lower methylation of the stress gene FKBP5 after treatment.

Adolescence

In the Strong African American Families program, 7 weekly family sessions in rural Georgia, youth who took part showed less inflammation and slower epigenetic aging years later than youth who did not.

One generation · ~25 years

A child raised by a parent whose trauma was treated grows up with steadier care and brings that into their own parenting. Home-visiting programs such as Nurse-Family Partnership have shown effects on children into their late teens.

2–3 generations · 50–75 years

Gaps in stress-related health could be expected to close over two to three generations, but only if the ongoing stressors shrink as well. This is an estimate from how the effects build up, not a measured result.

What makes it work

Culturally responsive therapists; naming racism-related stress directly instead of treating it as only personal; racial socialization that builds pride and coping skills (for example, the EMBRace program for Black families); partnerships with churches and community healers; and removing cost and access barriers.

Column heights and future paths are an illustrative teaching index. No study has measured stress load across these generations or forecast how long reversal will take. Present-day figures: CDC maternal mortality 2024 (44.8 vs 14.2 deaths per 100,000 live births); CDC provisional preterm births 2024 (14.9% vs 9.5%); Federal Reserve Survey of Consumer Finances 2022 (median wealth about $285,000 for white households vs about $45,000 for Black households). Related frameworks: historical trauma (Brave Heart), Post Traumatic Slave Syndrome (DeGruy), and weathering (Geronimus).

Finished the lesson?

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Six questions on DNA and the Epigenome. Rate how sure you are for each one. Your answers are anonymous and add to the class results. Or practice with a timed game, alone or with classmates.

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