The income per capita in Phoenix is 16% lower than the national average. The median household income in Phoenix is 12% lower than the national average. Male median earnings are 41% higher than female median earnings. The unemployment rate in Phoenix is 11% higher than the national average. The poverty level in Phoenix is 49% higher than the national average.
One major internal environmental influence that affects gene expression is gender, as is the case with sex-influenced and sex-limited traits. Similarly, drugs, chemicals, temperature, and light are among the external environmental factors that can determine which genes are turned on and off, thereby influencing the way an organism develops and functions.
This is one explanation of how environment can influence the extent to which a genetic disposition will actually manifest. The interactions of genes with environment, called geneâenvironment interactions, are another component of the natureânurture debate.ne way to determine the contribution of genes and environment to a trait is to study twins. In one kind of study, identical twins reared apart are compared to randomly selected pairs of people. The twins share identical genes, but different family environments.