ÁñÁ«ÊÓƵ

Tomorrow's Children, a film first seen in the US in 1934, features a courtroom battle over sterilisation. An evil-looking young man with a violent history is spared the operation because of his political connections. A young woman, of apparently impeccable character but from a family marked by alcoholism and mental handicap, is ordered to be sterilised. She gets a last-minute reprieve when her drunken mother confesses that her daughter was adopted. The tale implies that decisions about who shall reproduce will be based on power rather than biological fitness. As the authors of this book say, it contrives to be both rabidly hereditarian and anti-eugenic.

It is one of many examples which Dorothy Nelkin and M. Susan Lindee recount in their survey of popular ideas of the meaning of biological inheritance. They want to assess the cumulative impact of thousands of such items, some of them easy to read, some - like this one - more ambiguous. As "gene talk" grows more widespread with the advent of the human genome project, they want to ask what powers are being ascribed to the gene, and why.

It is easy to collect examples of gene talk and imagery; easier now than it has ever been. But it is much harder to judge their overall effect. Once you accept that the representations of the gene in popular culture are as significant as scientific pronouncements there is an effectively unlimited amount of material to consider.

As those who are familiar with Nelkin's many other books on relations between science and the public will expect, the key to her method is story-telling rather than sampling frames. Here, she has worked alongside a historian, which enriches the interpretation of present-day examples.

It is the intersection between folklore and current affairs which interests the authors. How do contemporary social problems and concerns and popular ideas of the meaning of inheritance interact and influence one another?

Folklore is important here not in the sense that this study actually taps the stories people tell each other - no urban myths of DNA here. It is more that one needs to be aware of a cultural level where old ideas and motifs are reconsidered and reworked to recognise what is happening when genes appear in cartoons, comic strips, commercials, or soap operas. And having identified such motifs there, it becomes easier to see them defining discussion, often unacknowledged, in newspaper editorials, Parliament, the law-courts, or in doctors' consulting rooms.

There are two main continuities which the authors argue are important. One is a fairly direct historical development from popular readings of eugenics, from around 1900 to 1935, to the current preoccupation with "genes for" a range of alleged traits from obesity to shyness. In a brief chapter on "The Eugenic Gene" they go some way to filling in a gap in the historical literature on eugenics by highlighting selections from the vast body of popular writing on the subject (an "informal survey" yielding at least 500 titles on the subject by non-scientists in the United States alone).

Although the Mendelian gene was already the vehicle for scientific investigation, the predominant term for the hereditary material in this period was the germplasm. And in the eugenic literature the role of the germplasm was to suggest that social problems had a bodily origin. Criminal behaviour or feeblemindedness, on the one hand, or the production of children fit for "better babies" contests on the other, both rested on biological inheritance, which could be extinguished but never denied. In the 1990s, the main scientific interest is ostensibly medical, but popular interest in the gene still speaks to concerns which were on display at the height of eugenics as a "civic religion", as they call it. "The almost magical powers of the germplasm resonate in remarkable ways with those of the highly medicalised and specific gene of the 1990s," they suggest.

Underlying all this was the second continuity which Nelkin and Lindee highlight, the germplasm as the biological essence of the person. The irreducible personal identity which is held to inhere in the genome is a secular version of the human soul in many examples of gene talk. This gives a new resonance to the loose talk of the more gung-ho molecular biologists, who have moved on from the talk of the secret of life to write of the human genome project as the Holy Grail of genetics, as decoding the Book of Man or simply as compiling the Bible.

The quasi-religious imagery obviously suits some purposes well, as for the US anti-abortionists who describe the DNA sequence as the "letters of a divine alphabet spelling out the unique characteristics of a new individual". But the strength of popular genetic essentialism has many other, less obvious effects. For example, it fuels a host of fictional narratives which depict dire consequences of genetic engineering, because it would amount to tampering with our sacred text. And it appears to be lending a newly fatalistic cast to childcare manuals. Nurture can only do so much, they now tell anxious parents. The fundamentals of your child's character and abilities are already inscribed in the genes, so your job is to learn to live with them.

Nelkin and Lindee's strongest interest, though, is in the coupling of this essentialist, determinist view of the gene with wider social and political agendas. This strand of the book builds on Nelkin's excellent earlier book with Lawrence Tancredi on testing and diagnostics. But this volume ranges more widely, reviewing all the ways depictions of the gene meet social needs and expectations.

They are ambivalent about the role of scientists in this process, sometimes suggesting that their work is misappropriated by other commentators but more often arguing that the promises made by scientists reflect beliefs about the power of heredity in the wider culture. Their conclusion is that, "the findings of scientific genetics - about human behaviour, disease, personality and intelligence - have become a popular resource precisely because they conform to and complement existing cultural beliefs about identity, family, gender and race". The book says little about how this convergence comes about, but suggests that it is a stronger cause for concern now than in the eugenic era because the new biomedical technologies have the power to make the scientific forecasts come true.

Overall, the book's claim that we are seeing a renewed emphasis on genetic determinism appears justified. The picture Nelkin and Lindee paint relies on a synthesis of an impressively wide range of materials, virtually all from the US. It is a recognisable one, I think, for a British reader, although the detailed resonances of the "supergene" differ. My own impression is that British references to the power of the gene are more likely to be ironic in intent than American ones, although the "couch-potato gene" is a good counter-example.

More seriously, one might argue that what we see here is simply a new phase of a constantly shifting balance between hereditarian and environmentalist views of the origins of human characteristics. Doubtless a similarly resourceful search would still yield many examples where nurture is ascendant over nature. But the material here certainly suggests strongly that Anglo-American popular culture is prey to a very simple "either-or" view of nature and nurture, and that nature is currently making the running.

It has become common for scientists and others concerned with the public understanding of the new genetics to write of the importance of "genetic literacy". But, as with the wider term scientific literacy, the implied analogy is false. Ordinary literacy is a largely technical ability, an all-or-nothing affair, a matter of a first-level decoding of marks on paper; illiteracy denotes an absence, which can be remedied.

Understanding the implications of genetic information does not fit this scheme. It is a matter of meaning. To define genetic literacy is to prescribe the proper set of meanings to attach to the vocabulary of genetics and inheritance. But there are meanings already attached to these terms, dispersed through the culture and being perpetuated and transformed as they are made to work for or against a complex of political and social interests. There may be good reason to work to alter public understanding of genetics, to help people play their part in a range of personal and social decisions. But any such efforts will have to engage with the understandings which are already abroad, as Nelkin and Lindee's book reminds us so well. Jon Turney is Wellcome fellow in the department of history, philosophy and communication of science, University College, London.