indeed.’40
When it comes to childhood, the key question is whether being a PROP taster sets you up for a lifetime of disliking the leafy green vegetables every nutritionist wants us to eat more of. Greens – especially those in the cabbage family – contain bitter-tasting glucosinolate compounds. One study suggested that PROP-tasting children were more likely to dislike raw broccoli, but not cooked broccoli. Another study found that when offered black olives, cucumber and raw broccoli, PROP non-taster children ate a larger quantity than tasters did.41 But when studies have looked at actual preferences rather than what children are prepared to eat in front of researchers, the signs are that PROP tasting in no way dooms you to dislike bitter vegetables. When 525 Irish children (aged seven to thirteen) were asked to record their intake and liking of cabbage, cauliflower, Brussels sprouts and broccoli over a three-day period, there were few significant differences between tasters and non-tasters.42 The supertasters did show a marginally lower liking for Brussels sprouts and non-tasters liked cauliflower the most. But when their consumption of bitter vegetables overall was totalled up and averaged out, there were no differences in intake for PROP tasters and non-tasters. In this study, being a PROP taster mattered less than the simple fact of whether these Irish children were boys or girls: girls tended to like bitter vegetables more, or at least to be polite enough to pretend that they did.
A 2013 survey of college students pointed to a similar conclusion. The supertasters and the non-tasters showed no marked difference in likes and dislikes for: Brussels sprouts, broccoli, cabbage, spinach, crushed red pepper, jalapeño peppers, red wine, beer, salad dressing, mayonnaise.43 The only substances that emerged as having significant negative connotations for PROP tasters were dark chocolate, coffee and chilli: the dark pungent end of the bitter flavour spectrum. The team of researchers concluded that environment mattered more than genes in determining preference. In America, they noted, many people ‘know they are not going to like spinach, tofu, liver or “healthy food” and learn that fast food burgers, soda pop and sweet breakfast cereals are delicious … before they ever take a bite’.44
Some of the most telling research to date on PROP tasters looked at how genes interacted with the food environment children were growing up in and confirmed that household income and access to good food are more critical in forming tastes than being a supertaster. Over five years from 2005 to 2010, researchers studied 120 New York children aged four to six. Their PROP status was measured and they were deemed to be living in either a ‘healthy food environment’ or an ‘unhealthy food environment’, as judged by the slightly crude method of dividing the number of healthy food sellers by the number of unhealthy food sellers within a half-mile radius of where they lived.45 In a healthy food environment, likes and dislikes followed the pattern that Ottolenghi – and common sense – would suggest. In this experiment, unlike the Irish one mentioned above, the PROP non-taster children who couldn’t detect bitterness did indeed show a higher acceptance of vegetables – with fewer dislikes – than taster children in the same healthy environment. The interesting – and troubling – result was what happened to the children in the unhealthy food environment. Here, the likes and dislikes of tasters and non-tasters were not very different. The big difference was in the BMI of the children. In the unhealthy environment, the non-taster children had a higher BMI than any of the other groups studied. Their average BMI was over 1.6, which counts as obese.
What matters most for determining whether your tastes will be healthy ones is not whether you have a sprout-hating gene but the way that your genetic predispositions interact with your food environment. Once environment is taken into account, being a non-taster poses bigger health risks in our current state of plenty and junk than being a supertaster. Several studies have now found that non-tasters – adults as well as children – are the ones who tend to have higher BMIs. The theory is that non-tasters – since they do not experience certain flavours with the same intensity – are more responsive to the influences around them, for good or ill. They learn their likes more easily than supertasters. In a healthy food environment, they will easily acquire healthy tastes. When offered vegetables, they are less likely than supertasters to dismiss them as too bitter. But if they learn to love the wrong foods, the non-tasters can find themselves – like those New York children – obese by the age of six.
So, no, you can’t blame your dislike of sprouts simply on having a faulty gene. If everyone’s first nibble of sprouts was of Ottolenghi’s own sprouts with caramelized garlic and lemon peel, charred in a hot pan until sweetly blackened at the edges, maybe they would be the most popular of all the vegetables. Perhaps your parents were sprout haters and – without meaning to – turned you against them. Or perhaps they forced them on you too vehemently. I know someone – a PROP supertaster, as it happens – who says she can never enjoy Brussels sprouts – though she has no quarrel with broccoli – because of memories of Christmas Day, when she was compelled by her parents to cut each hated sprout into quarters, and swallow them unchewed, like bitter pills. Maybe you never actually tasted sprouts because you ‘knew’ you wouldn’t like them, because in our society the child who loves sprouts is considered a little odd. When the food writer Michele Humes arrived in the US from Hong Kong, it took her a while to get her head around the concept that ‘children weren’t supposed to like vegetables’.46
Likes and dislikes cannot be reduced to molecules and genes. This is bad news for the more sensationalist health pages, which thrive on headlines like ‘Revealed: the Obesity Gene’. For the rest of us, it is – potentially – excellent information. It means that our food habits are not final and fixed but adaptable and open, if only we will give ourselves half a chance. We did not come into the world disliking bitter greens; we were taught to dislike them by our environment. Taste may be identity but it is not destiny. The hope – and admittedly it’s a slim one at present for the children whose dislikes are vegetables and whose likes are all junk – is that while we are stuck with our genes, the environment is something that can change.
The main way we learn to like foods is simply by trying them. The term ‘mere exposure’ was coined by Robert Zajonc in 1968.47 Zajonc’s thesis was that affection is triggered by familiarity; and that disliking, conversely, is fear of the novel. Some of Zajonc’s early experiments involved showing subjects complex shapes for very short periods of time. When the subjects were later asked to choose their favourite shapes from a line-up, there was a marked preference for the shapes that they had already encountered. Zajonc has suggested that there are similar forces at work when we favour Brie over Camembert.48 These cravings are a function of prior experience. One or other cheese may trigger a recognition in us that we cannot necessarily put into words. Zajonc later observed this phenomenon of ‘mere exposure’ at work across cultures and species.
It’s a truism that we know what we like and we like what we know. If you ask young children which foods they most detest, they tend to be the ones they have never actually tasted, often vegetables. To an adult, this sounds crazy: you can’t know if you hate something until you have tasted it. ‘Go on – you might like it!’ I find myself urging, ineffectually, at the dinner table. But to a child, there is nothing paradoxical in saying, ‘I don’t like it – I never tried it!’49 The foods that ranked highly on the ‘never tried’ list of a group of seventy American eight-year-olds included avocado (49/70 had never tried it), beetroot (48), prunes (43), collard greens (49), rye bread (43), lima beans (39), radish (38) and fried liver (55).50
The children’s book Bread and Jam for Frances by Russell Hoban is about precisely this dilemma. Frances – a young badger – does not want to eat anything except bread and jam. ‘How do you know what you’ll like if you won’t even try it?’ asks her father. Eventually, her parents give in to her demands for nothing but bread and jam. She is delighted. But over time, being excluded from what the rest of the family is eating makes her sad and she craves variety. One evening, Frances begs tearfully for some spaghetti and meatballs. Her parents express surprise, because they didn’t think she liked spaghetti. ‘How do you know what I’ll like if you won’t even try me?’ is her reply.
If liking is a consequence of familiarity, it follows that children are bound to like a narrower range of foods at first than adults, because they haven’t tried as many. Problems arise when parents