Do the genes have it?

It is easier to destroy trust than it is to build it up - a principle coined by the social scientists as the "asymmetry of trust" some time ago. Someone ought to coin a similar phrase about the asymmetry of explanations. In a controversial debate one side may be more easily summed up than the other by using a catchy phrase that lures public opinion.

This has become true in the debate about the degree to which our behaviour is genetically controlled. The image of a genetic programme, that makes our behaviour immutably female, white or gay, is catchier than the image of a mess of environmental factors interweaving with genetic factors in a jungle in which it is tricky to disentangle cause and effect.

The fact that one side of a debate can be simpler to explain than another has possibly been beneficial for homosexuals, who are likely to receive better treatment if their sexual leanings are deemed innate rather than voluntary. But the effect has not been beneficial for black people. This week we review two books-worth of responses to The Bell Curve, by Richard Herrnstein and Charles Murray.

The book caused a storm when it was published in the United States. It claims that the 15-point IQ difference between blacks and whites is due to genetic differences - and that the roots of most social problems lie in low intelligence.

In fact, as the responses demonstrate, it is much more complicated than that - possibly sufficiently complicated for the message of The Bell Curve to be anything from a gross distortion to just plain wrong. Also in this issue we describe research into the differences between men and women - differences between their brains and their behaviour. It turns out that this subject is a jungle as well. For example, the environment can affect our brains, altering their structure so that they make us behave differently. Such behaviour may later be labelled "innate".

And tiny genetic differences between two people may make them direct their behaviours slightly differently.

For example one child may watch television while the other plays football. Thus, if no one intervenes, they set up different environments for themselves which, over time, can cause major differences in their behaviour. Is this difference genetic or environmental? There is no slick term for summing up these interactions, and they can get lost in debates where feelings run high.

But there is another reason why these messages do not get through - biologists and social scientists rarely meet to discuss their work.

In the UK the Darwin seminars, held at the London School of Economics, and reported in the THES, have tried to remedy this. But in the US calm debate has been more difficult. A recent meeting between the disciplines in Baltimore, at the annual meeting of the American Association for the Advancement of Science, was described by an organiser as one of the first times the two had got together in the US to pool their findings on male and female behaviour.

The meeting seemed to be a model of informed discussion and mutual respect, with scientists on a spectrum from neuroscience to social research presenting their work.

Our reviewers conclude that The Bell Curve may cause scholars to avoid certain research - for example work that is inconsistent with environmental determination. This would be wrong. The work must be done and we must be brave about the results. But it must not be done, or reported, in a vacuum.

In such a sensitive area all researchers have a responsibility to listen to researchers in disciplines far from their own and to move forward, step by step, after proper communication - rather than proclaiming their ideas with a rhetoric that favours the side with the more glamorous case.