**13.6 Genetics and lava tubes**

Genetic enhancements may better adapt humans to living on Mars physically speaking, but what will it do to the human psyche? How will it affect behavior? Is it even ethical? What about the history of eugenics? The Nazi regime in Germany instituted various forms of eugenics, which led to unethical experiments and genocide against Jews and other perceived unworthy categories of people. While altering the human body to better tolerate solar radiation, for example, may seem like a logical idea, the human experience in this area is highly problematic. Ethical questions abound such as to whether or not those who receive enhancements have clearly provided authorization.

Other proposals include living inside lava tubes, as mentioned, utilizing 3D printing to construct habitat components, and creating human made subterranean habitats. While the external environment that impacts the surface is harmful to human life that currently exist, the places where humans actually live—that is, the ecosystems in the habitat structures—present potentially equally dangerous conditions as well.
