Does the environment exert an influence on the phenotype?

The phenotype may be altered (compared to the original situation conditioned by its genotype) by nongenetic means, instances: some hormones may cease to be secreted due to diseases but the genes that determine their secretion remain intact, a person can go to a hairdresser and change the color of his/her hair, plastic surgery can be performed to alter facial features of an individual. The colored contact lenses may be worn but a plant can grow beyond its genetically conditioned size by application of the phytohormones.

The Revealing cases of environmental influence on phenotypes are observed in monozygotic twins that have grown in various places. Generally these twins present extremely distinct phenotypical features due to the environmental and cultural differences of the places where they lived and to their different individual experiences in life.

(The Biologically programmed phenotypical changes like nonpathological changes of the skin color caused by sunlight exposure, tanning, or the variation of the color of some flowers according to the pH of the soil cannot be considered independent from genotype. In reality these changes are planned by the genotype as natural adaptations to environmental changes.)