Infinitesimal model

[1] In "The Correlation between Relatives on the Supposition of Mendelian Inheritance", the original 1918 paper introducing the model, Fisher showed that if a trait is polygenic, "then the random sampling of alleles at each gene produces a continuous, normally distributed phenotype in the population".

[2] However, the model does not necessarily imply that the trait must be normally distributed, only that its genetic component will be so around the average of that of the individual's parents.

[3] The model served to reconcile Mendelian genetics with the continuous distribution of quantitative traits documented by Francis Galton.

According to one research group, the model "…is obviously not an exact representation of the genome of any species," as humans do not have an infinite number of genes, "but is a useful assumption to make in genetic evaluation," such as "explaining the underlying variation of a trait.

"[7] Some phenotypes undergo evolutionary adaptation such that they involve a modest number of loci of large effect.