OBJECTIVE: Most research investigating sugar-sweetened beverages (SSB) and health, conducted at the individual or household level, ignores potentially important intra-household dynamics. We analysed self-reported consumption relationships between children and adults, and between children of different ages, as well as the associations between intra-household consumption, BMI and sociodemographic characteristics. DESIGN: A cross-sectional analysis of survey data from Kantar Fast Moving Consumer Goods panellists in September 2017. SETTING: Great Britain. PARTICIPANTS: Random sample of 603 households with children under 18 years who regularly purchase non-alcoholic beverages. RESULTS: Low- or no-sugar/diet beverages dominate consumption across all age categories, particularly children under 12 years. SSB consumption increased as children became older. Children's reported consumption of SSB and low- or no-sugar/diet beverages was positively associated with consumption by adults; a child in adolescence had over nine times the odds of consuming SSB (adjusted OR 9·55, (95 % CI 5·38, 17·00), P < 0·001), and eight times the odds of consuming low- or no-sugar/diet drinks (adjusted OR 8·12, (95 % CI 4·71, 13·97), P < 0·001), if adults did so. In households with multiple children, consumption patterns of older siblings were associated with those of the younger; notably a perfect correlation between children aged 0 and 6 years consuming SSB if siblings 13-18 years did so, and children aged 7-12 years had 22 times the odds of consuming SSB if siblings aged 13-18 years did so (OR 22·33, (95 % CI 8·60, 58·01), P < 0·001). CONCLUSIONS: Multiple policies, targeting children as well as adults, such as fiscal levers and advertisement restrictions, are needed to reduce and prevent the consumption of SSB.