Twisting the ladder of science: pure and practical goals in twentieth-century studies of inheritance.

In the twentieth century studies of inheritance have been driven by both practical and theoretical concerns. The metaphor of a ladder helps to illustrate how applied and pure interests have worked together in scientific development. This 'ladder' has significant 'twists' in it due to the unique nature of genetics, entwining the science of heredity with powerful and possibly compromising personal, social and commercial agendas. These implications are manifest in the history of agricultural research, eugenics, and the business of science. Today, as in the past, genetics is a prestigious science that requires cautious movement forward as human beings face its tremendous challenges and potential dangers.