Newman says that there’s a basic lack of “literacy” and understanding about genetic testing, among the public and even other health professionals. People are given false reassurances or made to panic (just because you have certain genetic variants, it doesn’t mean that you will develop a particular condition). Newman also makes the point that, in his field, counselling happens before and after testing and, while people with cancer or heart issues nearly always opt to have the test (as they can then take action to varying degrees), often people with conditions such as Huntington’s disease in their family decide not to go ahead because a diagnosis would change nothing for them. In any event, Newman says that, with genetic testing, while there are different levels, intensive counselling is always “absolutely key”.

Some concerns about the ultimate efficacy of certain home tests seem to emanate from the industry itself. I did a telomere-measuring test (a mouth swab) by Titanovo, based in north Colorado, which came back saying that my telomeres were too short, putting me at 10 biological years older than I am. However, when I contacted Titanovo, it explained that it had stopped telomere measuring and was now concentrating exclusively on its DNA-utilising “bioinformatics” health, fitness and wellbeing website (analysing client data from other genetic testing sites).
Most of the services we tested use genotyping to read your DNA. Genotyping looks for specific markers in your genetic code. For something like ancestry testing, genotyping is effective because it identifies known variants in your DNA. Scientifically speaking, genotyping’s weakness is that it can only recognize previously identified markers. This is one reason DNA tests’ accuracy relies so heavily on the DNA database size; there must be enough information available and identified genetic variants in the database to recognize new customers’ markers.
It’s easy to do these tests; it’s usually just a case of collecting your own samples at home, filling in short, basic questionnaires, posting the packages, and then logging on to interactive websites for confidential results (all the kits I tested used outside laboratories). With an array of price ranges and options, from one-off DNA-blitzes to targeting specific health areas, to fitness/wellness tracking, it’s no surprise that these kits are proving to be very big business and the field is primed to get even bigger, with a global market estimated to be worth around £7.7bn by 2022.
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