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‘Health Chatter’: Research Department of Behavioural Science and Health Blog



Letting your imagination run wild – genetic testing for risk of weight gain

By Susanne F Meisel, on 5 April 2013

These are exciting times for people working in genetics.  The field has become trendy.  ‘DNA’, ‘genes’ and ‘genetic code’ are no longer specialist terms, but used casually in everyday language. The media love ‘The gene for’ stories  and attributing individual differences to biology and less to environment is becoming commonplace.  I recently read an interview with a singer who explained that she could not imagine being anything else but a singer, because singing ‘was in her DNA’. If this still does not convince you: The pop band ‘Little Mix’ recently released a new song titled ‘DNA’ (http://www.youtube.com/watch?v=D3h-lLj3xv4).

Why the fascination with genes?  To a degree, it appears to stem from the inherent assumption that our genes can give us insights into ourselves that would otherwise remain inaccessible. Although our DNA is  99.9% identical, this is not interesting – it is all about the tiny bit of difference, the bit which sets us apart and makes us unique.

Companies have been quick to capitalise on our curiosity of what would be possible once the Human Genome was decoded.  Genetic tests for an array of traits and conditions, including those that are common and driven by lifestyle, such as obesity or heart disease, are already available over the Internet.  So far, we are not sure about the effects of giving this type of information to people. It could be that people will use it to prevent the condition. Alternatively, it could be that they become fatalistic or complacent. I have written in more detail about the current debate in a previous blogpost ( http://tinyurl.com/bve6y2m).  I hope to add some evidence to the debate by looking at the psychological and behavioural consequences of receiving genetic test feedback using obesity as an example for a very common, very complex condition.

Because we do not know yet how people react to knowing about their genetic susceptibility to weight gain, it would be unwise to give them this information right away.  Instead, we set up an online study where people were asked to imagine their reactions to receiving a ‘higher-risk’ or an ‘average-risk’ genetic test result for weight gain. They were then asked questions on a broad range of feelings and behaviours. We included 2 sets of people, nearly 400 students, who were predominantly of healthy weight and almost as many people from the general public who were or had been overweight.

Results showed that people in both groups reported to be more motivated to make lifestyle changes after imagining getting a ‘higher’ genetic risk result than after imagining getting an ‘average’ genetic risk result. On average, negative feelings and feelings of fatalism were anticipated to be very low and did not differ between risk scenarios. Those who were already overweight or obese were more likely to think that in comparison with an ‘average’ genetic risk result, receiving a ‘higher’ genetic risk result would offer them an explanation for their weight status.  Finally, people in both groups thought that they would be more likely to seek out information about what their result means in the ‘higher-risk’ than in the ‘average-risk’ scenario.

These findings are good news, because they suggest that giving people feedback for susceptibility to weight gain is unlikely to have unanticipated negative effects, and may even be motivating.  Furthermore, people who are already overweight may also benefit from genetic feedback.  However, these findings may not hold up once people are actually given genetic test feedback, because they only tell us about what people think they might do – and people find it generally quite difficult to imagine to be negatively affected by an event.  The next step is now to give people ‘real’ genetic feedback for risk of weight gain to discover the effect of this type of information.



Meisel, S. F., Walker, C., & Wardle, J. (2011). Psychological Responses to Genetic Testing for Weight Gain: A Vignette Study. Obesity (Silver Spring); 20 (3).DOI: 10.1038/oby.2011.324


Looking into the genetic crystal ball – A personal account of taking a direct-to-consumer genetic test

By Susanne F Meisel, on 25 November 2011

There it sits, on the counter, the vial which holds the key to knowledge, everything from ancestral lineage over earwax texture to my memory capacity. My strengths and weaknesses, the key to who I am…at least in genetic terms.

Proponents for direct to consumer genetic testing claim that a bit of spit contains everything I could possibly want to know about myself. The skeptics call it a genetic horoscope, as most results are no more accurate than traits attributed to star signs.

In recent years, companies emerged which offer genetic testing over the internet and promise to tell you more about your health and ancestry than you ever imagined.  With a couple of mouse clicks you can order one of their test kits, spit into a collection tube, seal it, send it back and within a few weeks you receive an email containing the link to a website which reveals your risk for a myriad of traits and diseases, half of which I would have trouble spelling, let alone pronounce.

Of course, doing a PhD in the subject calls for some self-experimentation, so my supervisor thought it would be a good idea for me to experience what this feels like … and this is how I ended up with a plastic tube full of spit.

It took me 3 days to send it off (apologies to the poor person in the lab who has to open that stinky tube). Why did it take me so long, I wonder? I consider myself as a curious individual interested in the latest scientific discovery, open to adopt new technologies…so why the hesitation?

I guess, because it felt like it could bring something to light which I might have happily left lurking in the dark. The 23andMe test I took reveals my risk for over 100 health conditions, some of which are quite severe, such as my risk for Huntington’s disease, Alzheimer’s or breast cancer. In addition, it shows my carrier status for various genetic diseases; my reaction to certain medications and finally personal traits such as memory capacity or the likelihood of ending up as an alcoholic. That, dear readers, is a lot of information. All at once, on one page.

Do I even want to know all of this? Even if I know that no cure exists for most of the diseases listed? The answer is: sort of. But, at this stage, only very few gene results can give meaningful risk estimations; most give only a minute indication of any change in risk – be it for better or for worse. The problem is also that conditions with exclusively genetic cause, such as Huntington’s Chorea, are listed with conditions where the picture is more complicated (for example in obesity).  This makes it very hard to know how much meaning to attach to a single risk result. I know I would be better off taking a long and hard look at my family history, if I wanted to get an idea of which diseases may be befalling me one day.

Nonetheless, I was incredibly curious to find out, and although my rational brain immediately told me that the results didn’t mean anything in the grander scope of things, they were all but unimportant. I felt something, and I definitely focused much more on the conditions where I was at a ‘higher risk’ than on those where I was classified as ‘average’ or ‘reduced risk’, regardless of what the actual risk estimation was.

The companies which provide direct to consumer genetic testing take quite a risk: They are providing medical results with minimal advice for conditions that many people may never have heard of, with risk estimations that don’t mean much objectively, but nonetheless seem to have an emotional impact – there is a lot of room for misunderstanding here.

For example, if I found out that my genetic risk of lung cancer is 6.8 % instead of the average of 6.2 %, then objectively that tells me that there is a whole host of factors other than my genes that play a role – however, because it is my personal  risk, it has some emotional meaning and in response

1. I could do the wise thing and stop smoking- advocates of these tests hope that we are using the information that we received to change our behaviour and prevent eventual illness

2. I could panic and ring my doctor for immediate 3 monthly check-ups – opponents of direct-to-consumer genetic testing fear that it might lead to unnecessary medical procedures

3. I could think that I will get lung cancer anyway and smoke even more, because of it – another concern of those cautioning against direct-to-consumer genetic testing

What will I do? What will other people do? I wouldn’t have been able to say before I took the test, because there is very little research on the subject to date. Now I know I will definitely not worry. But someone else might. It is an utterly individual experience, and there is certainly a good portion of narcissism attached.

Will I change anything? At the moment I am doing quite a lot of the ‘right’ things anyway, like being fairly active and eating sensibly (let’s keep quiet about the drinking) – but I’d like to think that it will have an impact when I am older. I think that it can be a positive influence on one’s health, because it raises awareness of potential illness and may be a motivation to look after oneself. Would I recommend it? Yes, but only if one is aware of the shortcomings of these tests, and if there is good information available about what the result means.


Despite all its criticisms, receiving those genetic results was a very unique experience, and I found out some things I am quite glad about. My eyes really are blue.  One thing, however, I didn’t look at: my genetic risk for Alzheimer’s disease. I think it would have been too disturbing to find out that I am more likely to get a severe illness for which there currently is no cure. But that was my individual choice. And that is what personalized genetic testing is all about.



Would you get tested? Why? Why not? Let me know below or send an email to Susanne.meisel.09@ucl.ac.uk