This is a simplified model of a quantitative character, but current research indicates that most quantitative characters do not follow this simple model. Epistasis among the genes influencing the character, dominance of some loci over others. Multiple alleles at loci that influence the character, with dominance among alleles. Quantitative characters are described and analyzed based on statistical parameters. In a population of organisms, the distribution of phenotypes for a quantitative trait will be determined by the different alleles present at the loci that influence the trait, along with environmental determinates of the phenotype.
Different genotypes produce different phenotypes, so the population has a range of phenotypes.
Most quantitative traits are influenced by environmental factors. Artificial selection, breed individuals and determine if the phenotype is transmitted to the offspring. Correlation among relatives, measure the phenotypic similarity among relatives. Twin studies, determine the phenotypic similarity among identical twins.