Quantitative inheritance and heritability scope
In a specified population model, narrow-sense heritability is the ratio of additive genetic variance to phenotypic variance.
Key knowledge
In a specified population model, narrow-sense heritability is the ratio of additive genetic variance to phenotypic variance. Genetic effects, environment and their interactions contribute to trait variation. Heritability depends on the sampled population and environment; it is not the fraction of one individual's trait caused by genes.
Values and equations
h² = VA/VP
- h²
- narrow-sense heritability 1
- VA
- additive genetic variance trait-unit²
- VP
- phenotypic variance trait-unit²
Conditions and scope
- The simple variance sum assumes no genetic–environment covariance and no unmodelled interaction.
- An estimated variance ratio does not establish immutability or explain differences between populations.
- The phenotypic variance VP must be strictly positive for h² = VA/VP to be defined. A population with no phenotypic variation does not have a defined value of this ratio.
Publication/edition date not stated. The original Summer Institute 5.1 URL is inaccessible in this continuation; retained original author/peer inspection is distinct. Other lecture slides contain simplified variance accounting, a genotype-frequency typo and dated clinical wording; these are not incorporated.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
- 5.1 Quantitative Traits and Heritability, slides 2–7University of Washington, Summer Institute in Statistical GeneticsTextbook chapter · PDF
- Lecture14: quantitative traits and heritability, selected variance-ratio and interpretation slides (date not stated)University of Washington, Genome Sciences 453Textbook chapter · PDFFresh actual official PDF text opened and selected ratio/scope sections inspected; no full-lecture or visual-formula certification. Publication/edition date not stated. The original Summer Institute 5.1 URL is inaccessible in this continuation; retained original author/peer inspection is distinct. Other lecture slides contain simplified variance accounting, a genotype-frequency typo and dated clinical wording; these are not incorporated.
Evidence and review
Read additive/dominance variance, explicit independence model and population-dependent h² definition; no individual causal fraction inferred.
The phenotypic variance VP must be strictly positive for h² = VA/VP to be defined. A population with no phenotypic variation does not have a defined value of this ratio. GS453 Lecture14, PDF pp11–12,18–19,24–25: narrow-sense variance ratio and population/environment interpretation. Fresh actual official PDF text opened and selected ratio/scope sections inspected; no full-lecture or visual-formula certification.
2026-10-10 · Independent AI editorial review: All 115 actual compact claims, hypotheses, equation/variable/unit tables and 251 origin semantic links independently read. All exact author source-binding rows and disclosed extents assessed; targeted original bodies or specifically identified indexed primary passages rechecked below. All retained biology compact records read for combined breadth. Independent AI editorial content and practical common-core inventory review; no human specialist, degree/laboratory proficiency, whole-textbook certification or experimental replication. Receipt: biology-independent-content-inventory-review.1.
Entry details
Permanent link to this entry ↗- Record identity
- uni-bio-quantitative-heritability
- Revision
- core.1.continuation-20261011.1
- Structured reference record
- University core expansion