Lawrence Wright is a staff writer on the New Yorker where parts of this book originally appeared so it is not surprising that the chapters read rather like magazine articles. They are, however, of a much higher standard than most such articles and it is clear that the author has thoroughly researched his subject. The bibliography alone fills 34 pages and he has consulted widely among scientists active in twin research, most notably Thomas J Bouchard who was the Institute’s 1995 Galton Lecturer. The result is a book well worth reading by anyone interested in the nature of human nature.

Fittingly Galton’s study of twins is regarded by Wright as “his most important legacy, upon which the science of behavioral genetics was created”. He notes that the reviews of Galton’s Hereditary Genius (1883) were very similar to those which greeted Herrnstein and Murray’s The Bell Curve (1994). To the hard line environmentalists, who are always with us, it seems that the mere suggestion that genes play an important role in the development of human behaviour is anathema.

However, although the initial reaction to Galton was unfavourable, by the start of the 20th century his views were becoming widely accepted and this led to the start of the eugenics movement, then closely allied to human genetics, in both of which twin research played, and still plays, an important part. Then, as Wright relates, in the 1930’s important twin research at the Maxim Gorky Institute in Moscow was abruptly ended because Marxist theory was based on the idea that people were the product of their environment, not their genes. Applied to agriculture by T D Lysenko this theory led to massive crop failures and widespread famine but continued to be part of orthodox Soviet belief until 1964.

Meanwhile in Nazi Germany human genetics and eugenics ceased to be scientific disciplines and were distorted in insane attempts to ‘prove’ that one race of mankind, unsurprisingly Germans, was in all respects superior to all others. At its extreme this led to the experiments of Mengele using twins which apart from being sadistic were totally without scientific value.

The suppression of Soviet twin research and its perverted use by the Nazis seriously hampered its progress for many years. There are still those who see little point in the study of twins because they are wedded to the belief, to them politically correct, that the environment is, or should be, the sole or major factor in the development of a person’s behaviours. More understandably there are those who fear that twin studies could again be used for dubious political ends. While this is true, almost anything can be used for good or evil, it is unfortunate that twin research remains under suspicion in some quarters since the comparison of monozygotic twins reared apart is the most direct method we have of evaluating the relative importance of nature and nurture to human behaviour.

In recent years, as Wright shows, twin research has become at least fairly respectable and he gives a good account of the results being obtained. These do seem to show that genes are more important than the environment in determining an individual’s behaviour in many, perhaps most, respects. There are some unanswered questions and it is likely to be some time before we know reasonably exactly the ratios of nature to nurture in the development of the many aspects of human behaviour. Nevertheless Wright ends his book with the words “There is finally no escape from being the people we were born to be.” It seems that as we near the end of the 20th century our view of human nature is starting to resemble the view our ancestors had at its beginning. We don’t become. We are.

John Timson