 It should also be noted that, in agricultural breeding, the lines or other genealogically defined groups became called genotypes as well. Genotypes in this sense are classes of individuals related by genealogy from a common ancestor or set of ancestors. The relatedness takes a variety of forms—not only pure (inbred or cloned) lines, but also offspring of a given pair of parents or a set of ancestors or an open pollinated plant variety in which the genes vary within replicable bounds among the generations of individuals in the class. The corresponding phenotype is then the range of values of the trait or set of traits as they are observed to vary for the genealogically defined line or group in the given location(s) or situation(s). In this sense the phenotypes from different lines may overlap; organisms are divisible into phenotypes as classes for the purpose of quantitative genetic analysis not through “finer methods of measuring or description”, but because the lines or groups are separable. (Quantitative genetics extended to humans does not involve controlled breeding, but does rely on relatedness that differs between, say, monozygotic and dizygotic (i.e., fraternal) twins. Even though a twin pair is not conventionally referred to as a genotype, human quantitative genetics has followed the same idea for data analysis as used in agricultural breeding.)