A lot of company nowadays offer genetic kits directly to consumers who can then have their genome sequenced on the cheap and get informed about any risk of contacting a genetic disease. If a person’s genome suggests a risk of developing diabetes, would that person change his diet to reduce this risk? Oppositely, would that person think there’s no use in changing  behaviour since it’s all ‘written in stone’? University of Cambridge surveyed all the relevant studies they could find on the matter and found personal genetic information does little to nothing to alter behaviour.

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The researchers examined over 10,000 papers, but could only identify 18 studies which fitted their strict standards for the analysis. The compiled data suggests people who are informed of any genetic risk do little to change their behaviour. For instance, a person who might be made aware by a genetic test that they’re genetically at risk of developing lung cancer will keep smoking nevertheless. Similarly, those who were informed of a heart disease risk did not improve their exercise routine, in general.

“Expectations have been high that giving people information about their genetic risk will empower them to change their behaviour – to eat more healthily or to stop smoking, for example – but we have found no evidence that this is the case. But nor does the evidence support concerns that such information might demotivate people and discourage them from changing their behaviour,” says Professor Theresa Marteau, who led the study.

Our DNA is made up of 3 billion base pairs, with myriad possible sequences of the four chemicals (represented as A, T, G, and C) that form the “instruction book” for a human being. Sometimes, this code book has misspellings — mutations that make our organism function differently. These mutations can also make us more resilient or, conversely, predisposed to diseases ranging from cancer to heart failure. When a large number of people share the same mutations, these are known as single nucleotide polymorphisms (SNPs, pronounced “snips”). These SNPs are well documented and some, alone or in combination, are associated with diseases based on previous research. Using huge genetic libraries, companies like deCODE or 23andMe interpret this never ending sequence of A,T,G and C. And it all starts with a simple swab saturated with saliva.

Seeing how the interpretation of genomes made by companies like 23andme isn’t exactly an exact science, many have voiced concerns. In 2013 in the United States, the Food and Drug Administration ordered the company 23andme — still the biggest consumer genetics company — to stop selling its testing kits because of concerns about their accuracy and usefulness.

The present research suggests that isn’t that much to worry about. People won’t start changing their lives based on a genetic test. Marteau stresses that consumer genetic tests could still prove useful, though. Knowing there’s a pretty big chance you’ll get a certain disease could prompt some people to visit a doctor and have a physical screening. In medicine, the sooner you find a problem, the easier it is to solve it.

Reference: Hollands, GJ et al. The impact of communicating genetic risks of disease on risk-reducing health behaviour: systematic review with meta-analysis. BMJ; 15 March 2016; DOI: 10.1136/bmj.i1102.