Many of us have experienced intense cravings for dishes our mums or dads used to cook. Indeed, it would make sense that our parents’ cooking forever shapes our food preferences. But a study of 2,865 teenage twins has now found that the effects of family upbringing on people’s food preferences disappear as they start to make their own meal choices.
The research, published in the American Journal of Clinical Nutrition, is hugely important. It has long been held that targeting what people eat in childhood is key to influencing adult food choices, but this research puts that belief into question.
The study was conducted using a powerful method, collecting the food preferences of twins aged 18 to 19 years old. Twins inevitably share many aspects of their upbringing, but as individuals they will also have their own unique environments, such as their circles of friends. This makes it possible to examine what kind of environment has the greatest impact on their choices. What is more, by including fraternal twins (who share half their genes) and identical twins (who share all of their genes), the study was able to explore the relative impact of genes, shared environment and unique environment on preferences for a range of foods.
In line with similar studies with younger children, the research found that in older teenagers (18 to 19 year olds) genes do have an impact on food preferences. The proportion of the food preferences that are attributable to genes (and shared by identical twins) is slightly different for different food groups. Preferences for vegetables tend to have a stronger genetic component than preferences for starches such as bread, rice and cereals. Overall, the study estimated that food choice is approximately equally influenced by genetic, and environmental factors.
However, when looking at the influence of shared and unique environments on food preference, the relative impact differed with age. In younger children, the twins’ shared environment, such as the family, had a large influence on food preferences. But for the older teenagers, it was each individual’s unique environment, such as their group of friends, that had an influence on food preferences. Shared environment – such as their family upbringing – had no detectable influence on the older group’s preference for any of the foods included in the study.
Implications for public health
This is a stark finding that rather goes against the notion that you can promote healthier behaviour in an adult by getting them while they are young.
But all is not lost. These data come from older teenagers, who are 18 to 19 years old, and this has a bearing on our interpretation of the findings. Both teenagers and younger children are known to be more socially responsive than adults, meaning that they are likely to alter their behaviour to align with what they see others doing. Older teenagers, unlike children, are also eating with their social group rather than with their parents and family.
So this study may be capturing a pattern of eating that is the result of individuals aligning their preferences with a circle of friends rather than with the culture and memory of eating that their upbringing imbued them with. It is quite possible that in the following early years of adulthood, social influence becomes less important and upbringing once again impacts on food preferences.
It would be premature based on these findings alone to suggest there is no value in improving childhood and family diets. We know that obesity in childhood and adolescence predicts obesity in adulthood, implying that early patterns of eating continue into later life. But it is also clear that there is a need to balance family-oriented public health activities with those that improve the food environment outside the home, such as lowering the cost and increasing the availability of healthier food options. As the authors themselves acknowledge, this will require stronger engagement from government in moulding the food environment that we live in.