Abstract
Jaenisch and Bird explain how cells with the same DNA take different roles — and how methylation and histone marks carry those patterns forward without changing the genetic code. Diet, aging, and environment can shift expression and long-term disease risk; the genome integrates inner and outer signals within hard biological limits.
Jaenisch, R., & Bird, A. (2003). Epigenetic regulation of gene expression: How the genome integrates intrinsic and environmental signals. Nature Genetics, 33(Suppl), 245–254. DOI
Key findings
- Same genes, different lives — One genome builds many cell types; stable expression patterns set during development and persist across divisions — epigenetic, not a DNA rewrite.
- Two main levers — DNA methylation and histone modifications are the core machinery that turns genes up or down — the map this review consolidates.
- Context leaves traces — Diet, stress, and exposure can influence methylation and disease risk over time — the body listens to environment within genetic constraint.
- Real but bounded — Plasticity is genuine; it does not mean every thought or coaching metaphor freely reprograms the genome — development, aging, and disease biology still set the frame.
Limits
A 2003 synthesis — directionally still cited, not the latest single-cell or transgenerational detail. Responsive expression is not proof that belief alone overrides sequence; pop epigenetics often overshoots what this paper actually claims.
Application
When genetic fatalism shuts down your options — or pop science promises that mindset alone rewires DNA — this review helps you separate what is tunable (stress load, sleep, exposure, expression) from what is constrained (sequence, serious disease risk). See Biological agency.