Explain how Hox genes influence animal development.

An example is a mutation that gives a fruit fly two sets of front wings, so it has a total of four wings instead of the usual two.

Hox genes are regulatory genes that will influence the expression of other genes. They are often implicated in body segment development. This is why Hox mutations are usually lethal - with wrong body segmentation, the necessary parts for survival will not be there. However, some mutations are survivable. An example is a mutation that gives a fruit fly two sets of front wings, so it has a total of four wings instead of the usual two.