Phenotype

A phenotype is an observable and measurable trait (in the broadest sense; e.g., size, pigmentation, behaviors, social interactions, etc.) that results from a combination of an organisms underlying genotype and from environmental effects on development, behavior, etc. Some phenotypes have a strong genetic basis while others have a very low level of heritability. If a trait has no genetic basis and is only a result of environmental effects (such as haphazard morphological physical damage that was not correlated with any genetic predisposition) it is not a phenotype.

Pleiotropy and Genetic Heterogeneity are concepts that are involved in understanding the connection between genotypes and phenotypes.

In humans stature is a common example of a phenotype with both a genetic (e.g., inherited growth factor activities) and environmental (e.g., nutrition) component.