Health professionals and parents appear to disagree about what determines children’s food preferences. While the former often take the view that healthy foods and the absence of “junk food” in the home will lead to healthier choices and eating habits, parents tend to focus on the individual likes and dislikes of their children, sometimes struggling to feed healthy food to a child “born with” a dislike of vegetables. And how many times will you have heard a parent say “my first was fussy from the start but my second is much more laid back”?
New research suggests that parents may not be so wrong after all. The results of a study we carried out of more than 1,300 pairs of three to four-year-old twins showed that food likes and dislikes are to some extent determined by their genes.
Twin studies, in which the similarity between pairs of identical twins is compared with that between non-identical pairs, allow scientists to tease apart these influences. If identical twins are more similar than non-identical twins in some behaviour traits, for example, then genes are likely to be involved. At the Health Behaviour Research Centre at UCL, we decided to use the Gemini cohort – a long-term study of 2,400 pairs of twins – to study food preferences. We’ve followed them since soon after their birth in 2007 and 1,300 are still providing valuable data nearly seven years later.
In 2010, when the children were around three, we asked their parents to complete a food preference questionnaire asking about their twins liking for 114 different foods in six categories: fruits, vegetables, protein foods, dairy foods, carbohydrates and snacks. Predictably perhaps, vegetables were the least liked food and snacks the most liked.
We also found that the food preferences of identical twins were much more similar than those of non-identical twins suggesting that preferences are to some extent inherited from parents. Statistical analyses then provided estimates of the contribution of genes and the environment to these preferences.
What emerged from these analyses was that around half of children’s liking for fruits, vegetables and protein foods can be attributed to genetic factors and the remainder to environmental factors like what parents choose to feed their children and foods available in the home. The picture was somewhat different for carbohydrates, dairy foods and salty and sugary snacks, liking for which is determined more by the environment, and only around 30% by genetic factors.
Most highly heritable appeared to be children’s liking for vegetables (54%) and fruit (53%) with protein foods close behind (48%). On the other hand, the environment played a larger part in liking for the other food groups: snacks (60%), carbohydrates (57%) and dairy foods (54%).
The findings support the assertions of health professionals that the home environment exerts a strong influence on children’s liking of the high-calorie foods implicated in excessive weight gain. However, they also suggest that parents are right in identifying innate differences in liking, particularly for the low-calorie nutritious foods that parents and health campaigners try to encourage. We know that children are born with a liking for sweet tastes and a dislike of bitter or sour tastes and this may partly explain the pattern of findings.
While the genetic effects on food preferences suggested by this study, published in the American Journal of Clinical Nutrition, are large, it’s clear that a child’s actual experiences with food are very influential. And a substantial body of research has shown that food preferences can be changed, particularly in very young children. Repeatedly offering small quantities of healthy foods and acting as a role model by eating and enjoying these foods, for example, have been shown to be highly effective in increasing children’s food acceptance. And so-called “covert control” can discourage unhealthy eating habits and food preferences by simply limiting the availability of high fat and high calorie snacks in the home.
There is no doubt that parents would feel reassured to know that although genes play a part in their children’s food preferences, there are scientifically tested strategies to help them to create a healthy home environment and happy mealtimes, even with fussy eaters.