Objective The present study aimed to define the complexity of the relationships between the family environment, health behaviours and obesity. A conceptual model that quantifies the relationships and interactions between parent factors, family environment, and certain aspects of children's behaviour and weight status is presented. Design Exploratory structural equation modelling was used to quantitatively model the relationships between parent, child and family environmental factors. Setting Adelaide, South Australia. Subjects Families (n 157) with children aged 5-10 years completed self-reported questionnaires, providing data on parents' knowledge, diet quality and activity habits; child feeding and general parenting styles; and the food and physical activity environments. Outcome variables included children's fruit and vegetable intake, activity and sedentary habits and weight status. Results The proposed model was an acceptable fit (normed fit index = 0.457; comparative fit index = 0.746; root-mean-squared error associated = 0.044). Parents' BMI (β = 0.32) and nutrition and physical activity knowledge (β = 0.17) had the strongest direct associations with children's BMI Z-score. Parents' dietary intake and energy expenditure behaviours were indirectly associated with children's behaviour through the creation of the home environment. The physical activity and food environments were associated with children's sedentary (β = -0.44) and activity habits (β = 0.29), and fruit and vegetable intake (β = 0.47), respectively. Conclusions A conceptual model that quantifies the complex network of family environment factors influencing children's behaviour and weight status is presented. The model provides a basis for future research on larger representative samples with a view to guiding obesity prevention interventions.