Twin Study Suggests Food Fussiness Is a Largely Genetic Trait

Fussy eating is mainly influenced by genes and is a stable trait lasting from toddlerhood to early adolescence, finds a new study led by researchers from UCL, King’s College London and the University of Leeds.

The study, published in the Journal of Child Psychology & Psychiatry and funded by the UK mental health charity MQ Mental Health Research, compared survey results of parents with identical or non-identical twins in England and Wales from the ages of 16 months to 13 years.

The research team found that average levels of food fussiness were relatively stable during this period, peaking somewhat around the age of seven and declining slightly after that.

They concluded that genetic differences in the population accounted for 60% of the variation in food fussiness at 16 months, rising to 74% and over between the ages of three and 13.

Environmental factors shared between twins, such as the types of foods that are eaten at home, were found to be significant only in toddlerhood, while environmental factors unique to each twin (i.e., not shared by co-twins), such as individual personal experiences (e.g., having different friends), became more influential in later years.

Food fussiness describes the tendency to eat a small range of foods, due to selectivity about textures or tastes, or reluctance to try new foods.

Lead author Dr Zeynep Nas (UCL Behavioural Science & Health) said: “Food fussiness is common among children and can be a major source of anxiety for parents and caregivers, who often blame themselves for this behaviour or are blamed by others.

“We hope our finding that fussy eating is largely innate may help to alleviate parental blame. This behaviour is not a result of parenting.

“Our study also shows that fussy eating is not necessarily just a ‘phase’, but may follow a persistent trajectory.”

Senior author Dr Clare Llewellyn (UCL Behavioural Science & Health) said: “While genetic factors are the predominant influence for food fussiness, environment also plays a supporting role.

“Shared environmental factors, such as sitting down together as a family to eat meals, may only be significant in toddlerhood. This suggests that interventions to help children eat a wider range of foods, such as repeatedly exposing children to the same foods regularly and offering a variety of fruits and vegetables, may be most effective in the very early years.”

The research team analysed data from the UCL-led Gemini study, the largest twin cohort ever set up to study genetic and environmental contributions to early growth, which involves 2,400 sets of twins.

Parents filled in questionnaires about their children’s eating behaviours when the children were 16 months, three, five, seven and 13 years old.

To disentangle genetic from environmental influences, the researchers compared the similarity in fussy eating between non-identical twin pairs, who share 50% of their genes, with the similarity between identical twin pairs, who share 100% of their genes.

They found that non-identical twin pairs were much less similar in their fussy eating than identical twin pairs, indicating a large genetic influence.

The team also found that identical twin pairs became more different to each other in their fussy eating as they got older, indicating an increase in the role of unique environmental factors at older ages. (Any differences between identical twin pairs are down to unique environmental factors, as identical twin pairs share both their genes and certain aspects of their environment that make them more similar to each other.)

Unique environmental factors accounted for about a quarter of individual differences between children in fussy eating by ages seven and 13, the researchers estimated.

Shared environmental factors, meanwhile, accounted for a quarter of individual differences between children in food fussiness at 16 months, with a negligible effect in later years.

Senior author Dr Alison Fildes (University of Leeds) said: “Although fussy eating has a strong genetic component and can extend beyond early childhood, this doesn’t mean it is fixed. Parents can continue to support their children to eat a wide variety of foods throughout childhood and into adolescence, but peers and friends might become a more important influence on children’s diets as they reach their teens.”

Among the study limitations, the researchers noted that there were fewer participants at age seven (703 children) compared to other time points and that the study sample had a large proportion of white British households of higher socio-economic backgrounds compared to the general population of England and Wales.

In future, the team said, research should focus on non-western populations where food culture, parental feeding practices and food security may be quite different.

Reference: Nas Z, Herle M, Kininmonth AR, et al. Nature and nurture in fussy eating from toddlerhood to early adolescence: findings from the Gemini twin cohort. J Child Psychol Psychiat. 2024. doi: 10.1111/jcpp.14053

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