Nature and nurture in fussy eating from toddlerhood to early adolescence: findings from the Gemini twin cohort.

BACKGROUND Food fussiness (FF) describes the tendency to eat a small range of foods, due to pickiness and/or reluctance to try new foods. A common behaviour during childhood, and a considerable cause of caregiver concern; its causes are poorly understood. This is the first twin study of genetic and environmental contributions to the developmental trajectory of FF from toddlerhood to early adolescence, and stability and change over time. METHODS Participants were from Gemini, a population-based British cohort of n = 4,804 twins born in 2007. Parents reported on FF using the Child Eating Behaviour Questionnaire 'FF' scale when children were 16 months (n = 3,854), 3 (n = 2,666), 5 (n = 2,098), 7 (n = 703), and 13 years old (n = 970). A mixed linear model examined the trajectory of FF, and a correlated factors twin model quantified genetic and environmental contributions to variation in and covariation between trajectory parameters. A longitudinal Cholesky twin model examined genetic and environmental influences on FF at each discrete age. RESULTS We modelled a single FF trajectory for all children, which was characterised by increases from 16 months to 7 years, followed by a slight decline from 7 to 13 years. All trajectory parameters were under strong genetic influence (>70%) that was largely shared, indicated by high genetic correlations. Discrete age analyses showed that genetic influence on FF increased significantly after toddlerhood (16 months: 60%, 95% CI: 53%-67%; 3 years: 83%; 81%-86%), with continuing genetic influence as indicated by significant genetic overlap across every age. Shared environmental influences were only significant during toddlerhood. Unique environmental influences explained 15%-26% of the variance over time, with some enduring influence from 5 years onwards. CONCLUSIONS Individual differences in FF were largely explained by genetic factors at all ages. Fussy eating also shows a significant proportion of environmental influence, especially in toddlerhood, and may, therefore, benefit from early interventions throughout childhood. Future work needs to refine the FF trajectory and explore specific trajectory classes.