It is a matter of scientific debate to what extent intelligence is hereditary. However, in a relatively broad part of the public the opinion prevails that intelligence is to a large extent hereditary, which means that it can only be minimally improved through social intervention. The book presents the scientific methods for determining heritability in the individual. It is clear from these methods that there can be no general value for heritability of intelligence, and that a heritability value says practically nothing as to the extent to which intelligence can be altered. The volume traces the history of research on the heritability of intelligence. The discipline is manifestly plagued by dubious practices and has caused social damage on a large scale, for example in the context of eugenics, immigration or education policy.