Norms of Reaction - Misunderstanding Genetic/environmental Interactions

Misunderstanding Genetic/environmental Interactions

Popular non-scientific or lay-scientific audiences frequently misunderstand or simply fail to recognize the existence of norms of reaction. A widespread conception is that each genotype gives a certain range of possible phenotypic expressions. In popular conception, something which is "more genetic" gives a narrower range, while something which is "less genetic (more environmental)" gives a wider range of phenotypic possibilities. This limited conceptual framework is especially prevalent in discussions of human traits such as IQ, Sexual orientation, altruism, or schizophrenia (see Nature versus nurture).

Popular conception of genotype/phenotype interaction

TRAIT SCALE <--6----------5----------4----------3----------2----------1----------0--> ^ (Genotype A) ^ ^ (Genotype B) ^ | | | | Environ <------> Other Environ <------> Other extreme extreme extreme extreme

The problem with this common simplified image is not that it does not represent a possible norm of reaction. Rather, by reducing the picture from two dimensions to just one, it focuses only on discrete, non-overlapping phenotypic expressions, and hides the more common pattern local minima and maxima in phenotypic expression, with overlapping ranges of phenotypic expression between genotypes.


Read more about this topic:  Norms Of Reaction

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