Understand the idea
Gene expression depends on regulatory processes, including chemical marks associated with DNA and chromatin. These processes help different cell types use the same genome differently; environmental influences can also affect regulation. [S10] Heritability describes the contribution of genetic variation to variation in a trait within a studied population and environment. It is not the genetic percentage of one person, nor a guarantee that intervention cannot matter. [S11]
Worked example
Imagine two gardens planted with varied seeds. Within a uniformly watered garden, differences among plants may be strongly associated with seed variation. Moving the entire garden into drought can still alter all outcomes. This analogy illustrates environmental dependence; it is not a heritability calculation.
Where the idea stops
Epigenetics does not imply that thoughts can rewrite any gene or that all acquired changes pass reliably to grandchildren. Cell-to-cell inheritance and inheritance across generations are different claims. [S10]
Connect it
Psychology and society: avoid turning group statistics into individual destiny.
Go deeper
Why does heritability not directly measure whether an intervention can work?
Sources
National Human Genome Research Institute, NIH · Research reference · Date: Date not established
Explains gene regulation and epigenetic marks without changing DNA sequence.
Link checked 2026-10-17 · Public webpage accessed; no specialist peer review of this brief.MedlinePlus Genetics, US National Library of Medicine · Research reference · Date: Date not established
Explains why population heritability is not an individual destiny percentage.
Link checked 2026-10-17 · Public webpage accessed; no specialist peer review of this brief.