Editing Genotype (section)

=== Polygenic traits ===
{{Main|Polygene}}

A polygenic trait is one whose phenotype is dependent on the additive effects of multiple genes. The contributions of each of these genes are typically small and add up to a final phenotype with a large amount of variation. A well studied example of this is the number of sensory bristles on a fly.<ref>{{Cite journal|last=Mackay|first=T. F.|date=December 1995|title=The genetic basis of quantitative variation: numbers of sensory bristles of Drosophila melanogaster as a model system|url=https://www.ncbi.nlm.nih.gov/pubmed/8533161|journal=Trends in Genetics|volume=11|issue=12|pages=464–470|doi=10.1016/s0168-9525(00)89154-4|issn=0168-9525|pmid=8533161}}</ref> These types of additive effects is also the explanation for the amount of variation in human eye color.