Strong Family-Level Clustering of Adolescent Weight Status Despite Limited Associations with Individual Parental Anthropometric and Metabolic Characteristics.

Objectives: Familial aggregation of obesity has been consistently reported; however, previous studies have predominantly relied on body mass index (BMI)-based associations and have dedicated insufficient time to examining the contribution of measurable parental biological traits to family-level clustering. We investigated associations between parental anthropometric and metabolic characteristics and adolescent weight status in families in which at least one parent had obesity, while exploring family-level clustering patterns. Methods: This cross-sectional family-based study included 34 families comprising 110 individuals (65 parents and 45 adolescents) consecutively recruited from primary care registries. Participants underwent anthropometric and biochemical evaluation, including indices of central body fat distribution. Linear mixed models were used to investigate associations between parental characteristics and adolescent BMI percentile while accounting for non-independence of observations within families. Results: Mean parental BMI was 31.37 ± 5.67 kg/m2, while 61.5% of parents had obesity. Among adolescents, 28.9% had BMI percentile between the 85th and 95th percentiles and 13.3% had a BMI percentile > 95th percentile. Strong family-level clustering of adolescent weight status was consistently observed across analyses, with intraclass correlation coefficients ranging from 0.716 to 0.728. In contrast, parental characteristics demonstrated limited explanatory contribution (marginal R2 0.028-0.044), while no isolated parental variable showed a significant association with adolescent BMI percentile. Conclusions: Strong family-level clustering of adolescent weight status was observed despite the absence of significant associations with individual parental anthropometric and metabolic characteristics, suggesting that familial obesity susceptibility may reflect shared influences extending beyond routinely measurable traits alone.