Genetics refers to that branch of biology that focuses on the mechanisms of heredity. Scientific knowledge about those mechanisms is rapidly increasing as we continue to uncover greater detail about the human genome. As we learn more and gain more control over the mechanism of heredity, the controversy surrounding genetics technology will increasingly take center stage in our politics. We may see government efforts to regulate or ban certain technologies or, more ominously, government efforts to coerce people to “improve the stock.” In that regard, the tragic experience with eugenics in the 20th century in Western Europe and the United States is a cautionary tale for the 21st century.

By 1900, eugenics had caught the popular imagination. The focus soon shifted, however, from encouraging the eugenic ...