This is an essay by Frederike Kaltheuner, a Mozilla Fellow researching trustworthy AI.

Imagine a world in which your breakfast, your holiday and even your roommate were determined by your genes. Sounds absurd? It’s already possible. AirBnB has partnered with 23andMe, a DNA company, to offer "heritage vacations." A German start-up claims to make muesli based on people’s DNA, and house-sharing platform SpareRoom trialed genetically matched roommates.

Ever since commercial genetic testing has become widely available, DNA-based predictions have exploded. While the first tests focussed on health and ancestry (the latter has been widely criticised), companies now claim that genetics can predict people’s ideal lifestyle, their intelligence, their personality and even their perfect romantic partner.

When I first encountered these tests, I thought they were a clever way to trick people into sharing their genetic data. Why send your DNA to a company to discover your ideal roommate when you could simply fill out a form or meet them for a coffee? Why predict personality based on DNA when this is what personality tests have done for years?

From Mozilla's Internet Health Report: '23 reasons not to reveal your DNA'

But as more companies offer increasingly bizarre predictions – one promises to reveal your “unique superhero traits” – it’s worth asking where the desire to find answers in genes comes from and where it leads us.

Companies that offer genetic predictions sell much more than DNA tests. They are also benefiting from – and ultimately spreading – the dangerous, yet incredibly compelling, idea that who we are is ultimately determined by biology.

This idea isn’t backed up by science. While researchers are indeed finding genetic variants associated with, for instance, intelligence, many commercial DNA tests assume that genes are both meaningful and deterministic in ways they simply are not. As Kevin Mitchell has argued in the Scientific American: “Developmental processes are subject to noise or inherent randomness at a molecular level. The genes can set the rules, but the outcome will vary — sometimes substantially — from run to run of the program.” In other words, no matter how good our understanding of the genetics, we will never be able to accurately predict intelligence from genomic information.

It’s not just in DNA testing that the idea of biological determinism is experiencing a revival. Angela Saini has documented the return of race science in her book Superior. The resignation last month of of Andrew Sabisky, an advisor to the British government, over remarks he made linking race with intelligence, precipitated serious public debate about "whether eugenics works."

Nowhere is this revival more evident than in the field of AI. Two years ago, two Stanford researchers published a now-infamous study that claimed AI can detect people’s sexual orientation from images of their face alone. The authors concluded that their findings strongly supported the controversial theory that sexual orientation is determined by differences in hormone exposure prior to birth.

The study was quickly denounced as deeply flawed, and even labelled phrenology, the nineteenth-century pseudoscience that claimed to predict character based on facial features. Yet its debunked conclusions have proven remarkably resilient. A 2017 headline in the Guardian still reads “New AI can guess whether you're gay or straight from a photograph.” Just last year, a WIRED podcast talked about the study’s conclusion as fact.

To look for answers in biology is seductive. It reduces the ambiguities of identity and gives answers to unknowable futures via a simple test. But it is also a slippery slope towards the eugenicist’s world view in which people are fundamentally different from one another, with some determined to be better than others, and where nature – not nurture or environment – is solely responsible for differences in achievement. 

As more brands partner with DNA testing companies as a way of recommending their products and services, they are inadvertently lending credibility to the idea of biological determinism – a belief which has been at the root of some of the greatest atrocities in human history. We can ill afford such ideas to regain traction. We must urgently push back.