Height in humans is influenced by numerous loci and has a relatively smooth distribution. It is thus a quantitative or continuous trait.
A quantitative trait locus (QTL) is a DNA territory correlated with a specific phenotypic trait that differs in extent and can be linked to polygenic effects, i.e. the product of two or more genes, and their habitat.
Social factors affect the overall survival of the bird.The amount of food an offspring get from the bird (in this case the mother), it determines the weight gain of the offspring, as well as the development of different skills and also its survival.
