The combination of genetic and environmental factors in determining a persons phenotype is called
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Heritability is a measure of how well differences in people’s genes account for differences in their traits. Traits can include characteristics such as height, eye color, and intelligence, as well as disorders like schizophrenia and autism spectrum disorder. In scientific terms, heritability is a statistical concept (represented as h²) that describes how much of the variation in a given trait can be attributed to genetic variation. An estimate of the heritability of a trait is specific to one population in one environment, and it can change over time as circumstances change. Heritability estimates range from zero to one. A heritability close to zero indicates that almost all of the variability in a trait among people is due to environmental factors, with very little influence from genetic differences. Characteristics such as religion or language spoken have a heritability of zero because they are not under genetic control. A heritability close to one indicates that almost all of the variability in a trait comes from genetic differences, with very little contribution from environmental factors. Many disorders that are caused by variants (also known as mutations) in single genes, such as phenylketonuria (PKU), have high heritability. Most complex traits in people, such as intelligence and multifactorial diseases, have a heritability somewhere in the middle, suggesting that their variability is due to a combination of genetic and environmental factors. Heritability has historically been estimated from studies of twins. Identical twins have almost no differences in their DNA, while fraternal twins share, on average, 50 percent of their DNA. If a trait appears to be more similar in identical twins than in fraternal twins (when they were raised together in the same environment), genetic factors likely play an important role in determining that trait. By comparing a trait in identical twins versus fraternal twins, researchers can calculate an estimate of its heritability. Heritability can be difficult to understand, so there are many misconceptions about what it can and cannot tell us about a given trait:
If heritability provides such limited information, why do researchers study it? Heritability is of particular interest in understanding traits that are very complex with many contributing factors. Heritability can give initial clues as to the relative influences of “nature” (genetics) and “nurture” (environment) on complex traits, and it can give researchers a place to start teasing apart the factors that influence these traits. Scientific articles for further readingMoore DS, Shenk D. The heritability fallacy. Wiley Interdiscip Rev Cogn Sci. 2017 Jan;8(1-2). doi: 10.1002/wcs.1400. Epub 2016 Dec 1. Review. PubMed: 27906501. Tenesa A, Haley CS. The heritability of human disease: estimation, uses and abuses. Nat Rev Genet. 2013 Feb;14(2):139-49. doi: 10.1038/nrg3377. Review. PubMed: 23329114. What is the genetic and environmental contribution to the phenotype?Genes play an important part in influencing phenotype, but genes are not the only influence. Environmental conditions, such as temperature and availability of nutrients can affect phenotypes. For example, temperature affects coat color in Siamese cats.
What is a combination of genes and environment?Epigenetics. The epigenome is the primary location of gene-environment interactions and can be altered by the environment both directly and indirectly. It literally means “on top of or in addition to genetics,” or basically factors outside of the genetic sequence.
What is a phenotype that is influenced by the environment called?Phenotypic plasticity refers to the observation that a given genotype expresses different phenotypes in different ecological settings. At its most basic level, the concept applies to any differences in trait means between environments.
What two factors determine the phenotype of a person?Phenotype refers to an individual's observable traits, such as height, eye color and blood type. A person's phenotype is determined by both their genomic makeup (genotype) and environmental factors.
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