The complete set of observable traits of the structure and behavior of an organism is called its phenotype. These traits arise from the interaction of its genotype with the environment. As a result, many aspects of an organism’s phenotype are not inherited. For example, suntanned skin comes from the interaction between a person’s phenotype and sunlight; thus, suntans are not passed on to people’s children. However, some people tan more easily than others, due to differences in their genotype: a striking example is people with the inherited trait of albinism, who do not tan at all and are very sensitive to sunburn.