from it at the dinner table.31 Researchers found that when they gave three groups of preschool children different varieties of tofu – one group had plain tofu, one ate it with sugar and one with salt – they quickly came to prefer whichever one they had been exposed to, regardless of their genes.32 It turns out that, so far from being born with genetically predetermined tastes, our responses to food are remarkably open to influence, and remain so throughout our lives.
If you want to know what foods a person does and does not like, the single most important question you can ask is not ‘What are your genes?’ but rather ‘Where are you from?’33 Had he lived in a part of the world where cornflakes are hard to come by, the cornflake boy would have had to find another way to annoy his parents. To a large extent, children eat – and therefore like – what’s in front of them, particularly in conditions of scarcity. ‘If you want your children to be less fussy about what they eat,’ a friend who had fallen on hard times during the recession advised me, ‘I can recommend poverty.’ It’s not really an option to be picky about the staple food of rice if you live in rural China.
Genes do make a difference – to the foods we like, the way we taste them and even how much we enjoy eating – but they turn out to be much less significant than the environment we learn to eat in. Contrary to our deepest beliefs about ourselves and our children, our likes and dislikes – the important ones, anyway, such as whether we eat enough vegetables or how much variety and balance we have in our diets – are much more about nurture than nature. Apart from changing the infants’ food environment, there was another bigger trick to Davis’s experiment, which she did not mention, perhaps because it is so obvious. She radically changed their social experience when eating, removing all extraneous social influence. In place of the hubbub of the family dinner table, the babies had only expressionless nurses who ‘might not comment’ in any way on their choices. The thought of being served in this silent, impassive way is creepy, particularly for the oldest children, who must have been as old as five by the time they left the orphanage. They ate without anyone caring what they ate; without any siblings fighting them for the last slice of pineapple; without any surrounding ideas about cuisine.
Davis was mistaken if she thought this was the way to discover the true nature of children’s appetites. Though the nutritional outcomes were excellent, it was a not-quite-human way to eat, and one which no child in a real situation will ever replicate. We cannot arrive at the truth about appetite by removing all social influences. Appetite is a profoundly social impulse. To a large extent, our likes and dislikes are a response to the environment we eat in. From our first toothless tastes, we are picking up cues about which foods are desirable, and which are disgusting, which sadly are so often the very ones the grown-ups most want us to eat.
The public discussion of eating habits is focused on temptation and the idea of resisting desirable foods. But if we look at eating through the eyes of a child, we see that disgust may be even more powerful than desire in forming our tastes. Our urge to avoid eating something that makes us feel sick is often at the root of disordered eating, as we swerve away from whole categories of foods that we imagine would make us feel queasy. The most common reason for disgust is nausea: anything eaten just before a bout of stomach bug may be hated for life. Psychologist Paul Rozin, the world’s leading expert on disgust, has argued that a central feature of disgust is ‘contagion: when a disgusting food touches otherwise acceptable foods, it renders them permanently inedible’.34 And yet most of the foods that we happen to find disgusting are not toxins but perfectly edible and wholesome foods. Brussels sprouts, for example.
If there is one food associated with personal dislikes in the Anglo-Saxon world, it is the Brussels sprout. Many people assume they have no choice in this matter – they just can’t stand them. Are they right? In an article singing the praises of Brussels sprouts, the great chef Yotam Ottolenghi noted that there was a ‘genetic explanation for why people either love or loathe’ these little green brassicas.35 Ottolenghi argued that being a sprout hater was likely to be a consequence of having a certain gene – TAS2R38 – which ‘makes a protein that reacts with a chemical called PTC to create the sensation of bitterness’. Could this really be true? Is there a molecular basis to our hatred – or otherwise – of green vegetables?36
Some people definitely taste certain flavours more acutely than others. To take one of the stranger examples, up to 30 per cent of the population cannot physically pick up on androstenone, one of the key aromas that make truffles such a luxury. If you served them a sumptuous plate of pappardelle with truffle shavings, they would have no idea why it was meant to cause such joy. A different minority have a heightened sensitivity to coriander leaf, making it taste soapy and gross, rather than herbal and fresh. And, as Ottolenghi says, we vary hugely in our response to bitter tastes. All babies find bitterness somewhat horrible, which is probably a survival mechanism, given that in the wild, toxic substances tend to be bitter. The bitter response of a newborn includes arched lips, a protruding tongue, an expression of anger and spitting: all pretty vivid signs that babies do not consider bitterness to be yummy. Over time, however, it is possible to learn to love bitter substances: witness the fact that the world’s two most popular beverages are coffee and beer.
Some learn to love bitterness; some tolerate it because they enjoy the buzz they get from a bottle of IPA or a cup of strong cafetière coffee; and some hardly taste it at all. Linda Bartoshuk of Yale University was the first to use the term ‘supertaster’ in the mid-1990s to refer to individuals with a heightened response to certain tastes, predominantly bitter ones (the phenomenon was first observed in the 1930s). Bartoshuk and colleagues found that there were significant genetic differences in the way we perceive bitterness. PROP (6-n-propylthiouracil) and PTC (phenylthioucarbamide) are chemical substances that either taste incredibly bitter or slightly bitter or of nothing at all, depending on whether you have the gene to taste them.37 Around half of us are medium tasters, a quarter are non-tasters and another quarter are supertasters. Women are more likely to be supertasters than men. Bartoshuk has shown that PROP supertasters have more taste buds on their tongue than non-tasters. There’s a very simple way to self-diagnose whether you are a supertaster or not. Swab your tongue with a little blue food dye and place a hole punch reinforcer ring on your tongue. Count how many pink bumps you can see inside the ring – these are the fungiform papillae, each containing 3–5 taste buds. If fewer than 15, you are a non-taster. If 15–35 you are a medium taster. If more than 35, you are a supertaster.
Psychologists got excited about the concept of PROP tasting, because it seemed to hold out – at last – the genetic key to likes and dislikes. Could bitter sensitivity be the secret of why some people eat unhealthy diets with few or no vegetables? Is it because they lack a gene for sprouts? The world of flavour must be a very different place to PROP supertasters and non-tasters and it would appear obvious that this would translate into food habits. When seventy-one women and thirty-nine men were asked to taste asparagus, kale and Brussels sprouts, the PROP supertasters did indeed find the vegetables to be more bitter and less sweet.38
The surprising thing, however, is that, from a mass of research into PROP tasting, very little does point to genes determining food choices, either in children or adults.39 Over time, your PROP status is not a particularly strong predictor of what your likes and dislikes will be. If anything, PROP non-tasters – the ones who can’t taste bitterness in the sprouts at all – are slightly more at risk of an unhealthy diet and weight than the PROP supertasters.
There’s clear evidence that PROP supertasters are more sensitive to certain flavours: the burn of chilli, the warmth of cinnamon, the acrid glow of coffee, the rasp of alcohol, the aftertaste of sweeteners and grapefruit – all these are perceived more strongly, often unpleasantly so. What is not so predictable is how this affects preferences. Given that supertasters perceive alcoholic drinks as more bitter, you’d expect them to drink less of them – indeed being a non-taster has been identified in some studies (though not others) as a risk factor for alcoholism: if whisky tasted like water, how easily it might go down. But a study of young adults found that being a PROP taster did not predict how much beer was drunk. After decades of enjoying countless glasses of wine from all the great terroirs in the world, the leading wine writer Jancis Robinson found out that she was a supertaster, something that in theory should make