Why Genetics Alone is Not Enough

Genomics is transforming how medicine researches, diagnoses and treats disease. Since the human genome was sequenced in 2003, personalised approaches have moved steadily from research into practice. Nutrition has joined that movement too, through the field of nutrigenomics.

But there is an important caveat that often gets lost in the enthusiasm: genetics alone is never the whole picture.

What nutrigenomics studies

The nutrition market is saturated with dietary approaches. They work well for some people and poorly for others, and part of that variation is genetic — our bodies differ in how they process nutrients and respond to particular eating patterns.

Nutrigenomics examines the interaction between diet and genes: how specific nutrients influence gene expression, and how genetic variation affects nutrient metabolism.

Why genetics is only part of the equation

Health outcomes emerge from the interplay of genetic, behavioural and environmental factors. Even where a genetic profile indicates susceptibility, whether a condition develops depends heavily on everything else.

Take obesity. Dietary factors — energy density, portion sizes, ultra-processed food availability — combined with sedentary lifestyles explain much of the global rise in obesity rates. Genes have not changed meaningfully over that period; environments have.

That said, genetics does influence how strongly individuals respond to those environments. Variants in genes such as FTO and MC4R affect appetite regulation and satiety signalling, which is part of why the same food environment affects people so differently. Obesity is genuinely multifactorial — hormones, sleep, medication, stress, socioeconomic circumstances, metabolism and genetics all contribute.

Where the evidence is solid — and where it isn't

Well supported: lactose intolerance (MCM6/LCT), caffeine metabolism (CYP1A2), alcohol processing (ALDH2), folate conversion (MTHFR), coeliac susceptibility (HLA-DQ2/DQ8), and familial hypercholesterolaemia.

Not well supported: the claim that genetic testing can identify whether you should follow a low-fat or low-carbohydrate diet for weight loss. Large randomised trials, including the DIETFITS study, tested this directly and found genotype did not predict which approach worked better. Participants lost comparable amounts on either.

Be sceptical of any service promising a genetically optimised diet plan that will succeed where others failed. That is not what the evidence currently shows.

What actually drives change

A systematic review by Stewart and colleagues (2018) examining behaviour change after direct-to-consumer genetic testing found the most meaningful outcomes occurred when testing was combined with lifestyle counselling and ongoing support — not when results were simply delivered as a report.

That finding is the practical heart of this article. A genetic result is information. What changes health outcomes is what happens afterwards: dietary support, activity, sleep, stress management, and having someone to ask questions of.

Our approach

Rightangled's DNA tests examine markers relating to nutrition, metabolism, intolerance and exercise response. Our blood tests measure cholesterol, HbA1c, vitamin and mineral levels — frequently the more directly actionable information, since they reflect your current state rather than a tendency.

All results are reviewed by our clinical team, which includes GPhC-registered independent prescribers, with medical oversight from our doctor, Dr Abdullah, so you receive interpretation and realistic context alongside your data.

Rightangled is a UK-registered online pharmacy — verify us with the General Pharmaceutical Council (registration number 9011933), see our LegitScript certification, and read independent patient reviews on Trustpilot.

References

Doo M, Kim Y (2015). Obesity: interactions of genome and nutrients intake. Preventive Nutrition and Food Science, 20(1), 1–7.

Mead MN (2007). Nutrigenomics: the genome–food interface. Environmental Health Perspectives, 115(12), A582–A589.

Stewart KFJ et al. (2018). Behavioural changes, sharing behaviour and psychological responses after receiving direct-to-consumer genetic test results. Journal of Community Genetics, 9(1), 1–18.

This article is for general information and does not replace personalised medical advice.