A new study has found that as a child enters late adolescence, the influence of genetics on food preference remain moderate and the effects of his or her upbringing on food preferences disappear. Instead, non-shared environmental factors have an influence on food preferences, which suggests that as the effects of family experiences disappear by young adulthood, the environment plays a much larger role.
A diet that is healthy and balanced is key to optional health in both the short and long term. Actual food choice is largely dependent on food preferences, which determine the intake of macronutrients (i.e. carbohydrates, fats, proteins, vitamins) and micronutrients (i.e. minerals, vitamins, antioxidants) and differ significantly among children and adults. Unhealthy food preferences can lead to poor dietary quality, increasing the risk of chronic diseases related to nutrition, and comorbidities such as type 2 diabetes. Therefore, understanding the factors that influence food preferences has important implications for clinicians and policy makers.
Prior research on twins has suggested that food preferences in children and adults is, to a large extent, influenced by genes and characteristics of the shared family environment (e.g. being raised in the same household), and that characteristics of the non-shared environment (e.g., that are unique to each child) have a minimal contribution in influencing food preferences. This seems logical as the home family environment is important for the eating behaviour of preschool children (e.g. food availability), given that the family setting is the key environment within which a child develops his or her behaviours.
Studies in adult twins have also demonstrated that genetics tend to have a moderate effect on food preferences in adulthood; however, the most significant influence on food intake and choice during adulthood is the unique, non-shared environment, with minimal evidence that the shared environment has a meaningful influence. This shows that shared environmental factors that play a role in influencing the development of food preferences in childhood are less significant in adulthood, but at what point the influence of the shared environment diminishes is unclear. Late adolescence is an important developmental change from childhood into adulthood that is marked by gains in independence; simultaneously, as adulthood approaches, the family remains an important but decreasing source of influence. To date, there had been no existing studies on the influence of genes and shared and unique environmental factors on food preferences in late adolescence.
A group of researchers, therefore, aimed to measure the relative contribution of genetic, shared and unique environmental influences on food preferences in older adolescents (18-19 years of age). They hypothesized that food preferences would be influenced by genetics at a moderate level, and be influenced by both the shared and unique environment. The researchers used data from the TEDS (Twins Early Development Study), a large population-based cohort of 2865 British twins, aged 18-19 years old, and born in England and Wales during 1994–1996. Self-report questionnaires were given to participants to measure food preferences of 62 individual foods. Food items were classified into 6 food groups (vegetables, fruit, dairy, meat or fish, starch foods, and snacks).
The findings, published in the American Journal of Clinical Nutrition, showed a moderate influence of genetics on variations in food preference in late adolescents; genetic factors had influenced a significant proportion of the variation in preference scores of all 6 food groups (vegetables, fruit, starchy foods, meat or fish, dairy, and snacks).However, the influence of the shared family environment had disappeared by this period of age and only characteristics of the environment unique to each individual twin (e.g. not shared by two twins in a family) had influenced food preferences, explaining for all of the remaining variance in food preferences. Put differently, early shared environmental factors between twin siblings (e.g., the household or school setting) did not seem to significantly influence food preferences in late adolescence.
These findings are in keeping with prior studies on factors influencing food preferences, which consistently indicated a moderate genetic influence on individual differences in food preferences. Notably, the results suggest that by the time individuals enter young adulthood or late adolescence, unique environmental influences replace significant shared environmental influences from childhood. Also, for adolescents, encounters with food occur outside of the family home, at an increasing extent.
In conclusion, both genetic and unique environmental factors influence food preferences of older adolescents. However, the findings of no significant effect of the shared environment on food preferences in late adolescence could suggest that early shared family experiences that shape food preferences in childhood may not have effects that carry on into adulthood. Overall, the findings show that food preferences are more or less equally influenced by genetic and non-shared environmental factors. Efforts to enhance nutrition of adolescents may, for that reason, be best targeted at the wider environment rather than the home. The researchers suggest that lowering the cost, increasing the availability, and promoting foods that are healthier are potential strategies that could be used.
Written By: Nigar Celep, BASc