Obesogenic genes versus environment
The authors of the NBER working paper conclude that genes rather than
environmental factors play the most important role in obesity, "contrary
to conventional wisdom".
This would explain why all dieting, exercise and weight reducing
medication seems to provide only temporary reductions in body mass: the
genes are unaffected by such interventions.
However, if some finding is contrary to conventional wisdom, a wise
author will think twice before concluding that everybody else was wrong.
Even apart from the futility of the debate - genes versus environment is
simply not a valid opposition because an obesogenic environment may have
more effect on genetically susceptible persons - there is a fatal logical
difficulty with the proposition that it's all about genes: the dramatic
increase in obesity prevalence over the past 30 years. From an
evolutionary point of view this would require that all of a sudden people
with these alleged obesity genes (and since environment doesn't matter,
they would have been obese) would have acquired an enormous procreation
advantage: only in that way can the existing gene pool be altered. We
think there is no need for a formal rejection of such a corollary: the
proposition sinks by simple common sense.
The authors reviewed the literature on correlations of weight between
family members, but this kind of studies tends to suffer from what one
might call a form of myopia: environmental exposures were too similar to
show effects on body mass. The authors of the NBER study would do well to
extend their literature review, for example by reading Rose's Strategy of
As for the BMJ publishing this news item: NBER working papers are
just that: working papers. They are not peer-reviewed. It would be good
if the BMJ were a bit more critical about such papers, even in the news
Competing interests: No competing interests