[foxyv]

> Where is the line between "gene therapy" to eliminate differences (such as deafness) and eugenics?

The difference is usually a matter of informed consent. Eugenics tends to be non-consensual. Sterilization or forced birth control for unwanted individuals. Murder of unwanted individuals. Involuntary genetic modification of unwanted individuals will probably pop up eventually.

Typically gene therapies are on living, consenting people with all the information to make a choice. It also doesn't usually result in germline modification. The sticky part is when you get to babies and fetuses. Can a mother consent for her fetus? What about germline modification? In-vitro gene therapy? Then you are getting into Brave New World territory.