Editing Genotype–phenotype distinction (section)

==Overview==
The terms "genotype" and "phenotype" were created by [[Wilhelm Johannsen]] in 1911,<ref>{{Cite journal |doi=10.1086/279202 |title=The Genotype Conception of Heredity |journal=[[The American Naturalist]] |volume=45 |issue=531 |pages=129–159 |year=1911 |last1=Johannsen |first1=W. |jstor=2455747|pmid=24691957 |pmc=4258772 }}</ref> although the meaning of the terms and the significance of the distinction have evolved since they were introduced.<ref>{{cite web |url=https://plato.stanford.edu/entries/genotype-phenotype/ |title=The Genotype-Phenotype Distinction |last1=Taylor |first1=Peter  |last2=Lewontin |first2=Richard |access-date=21 June 2017}}</ref>

It is the organism's physical properties that directly determine its chances of survival and reproductive output, but the inheritance of physical properties is dependent on the inheritance of genes. Therefore, understanding the theory of evolution via [[natural selection]] requires understanding the genotype–phenotype distinction. The genes contribute to a trait, and the phenotype is the observable manifestation of the genes (and therefore the genotype that affects the trait). If a white mouse had recessive genes that caused the genes responsible for color to be inactive, its genotype would be responsible for its phenotype (the white color).{{cn|date=March 2023}}

The [[Function (mathematics)|mapping]] of a set of genotypes to a set of phenotypes is sometimes referred to as the [[genotype–phenotype map]].<ref>{{cite journal |title=Genotype–phenotype mapping and the end of the 'genes as blueprint' metaphor |last1=Pigliucci |first1=Massimo |journal=Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences |year=2010 |volume=365 |issue=1540 |pages=557–566 |doi=10.1098/rstb.2009.0241 |pmid=20083632 |pmc=2817137 }}</ref>

[[File:De Albina y Español, Torna atrás (Juan Patricio Morlete).jpg|thumb|''De [[Quadroon|Albina]] y Español, [[Torna atrás]]''. Attributed to [[Juan Patricio Morlete Ruiz]] (1701-1770) In [[casta]] paintings, "torna atrás" described mixed-race individuals who expressed phenotypes dissimilar to their parents. In this painting, the daughter and mother are both of partial [[Sub-Saharan]] and European ancestry, yet have noticeably differing phenotypes.]]
An organism's genotype is a major (the largest by far for [[morphology (biology)|morphology]]) influencing factor in the development of its phenotype, but it is not the only one. Even two organisms with identical genotypes may differ in their phenotypes, due to [[phenotypic plasticity]]. To what extent a particular genotype influences a phenotype depends on the relative [[Dominance (genetics)|dominance]], [[penetrance]], and [[Expressivity (genetics)|expresivity]] of the alleles in question.{{cn|date=February 2025}}

One experiences this in everyday life with [[identical twins|monozygous (i.e. identical) twins]]. Identical twins share the same genotype, since their genomes are identical; but they never have the same phenotype, although their phenotypes may be very similar. This is apparent in the fact that close relations can always tell them apart, even though others might not be able to see the subtle differences. Further, identical twins can be distinguished by their [[fingerprint]]s, which are never completely identical.{{cn|date=March 2023}}