In the literature there currently exist two diametrically opposite hypotheses; while one school of thought argues that obesity is associated with hyper-responsivity or excessive 'wanting' for food, another line of argument postulates that obese individuals are in fact hypo-sensitive to the rewarding properties of food. This latter hypothesis is informed by evidence that the dopaminergic system is downregulated in the obese, which, in turn, is believed to lead to chronic over-consumption of food as a means to compensate for the deficit. Aims and hypotheses: With respect to the above proposed studies investigating the opioid and dopaminergic systems, in the first instance it will be of critical importance to demonstrate that the candidate genes (OPRM1 and DRD2) are associated with obesity. The proposed pilot work will enable us to determine whether associations exist between OPRM1, DRD2, and obesity and we feel that these data will add a major strength to our subsequent grant proposal. On the other hand, if we were to find support for the null hypothesis, that these genes are not associated with obesity, then we would not pursue this line of enquiry. Either way, we feel that the scientific quality of our proposal will be greatly enhanced through the procurement of this pilot data from the ALSPAC cohort. We aim to examine data from ALSPAC on genotype (OPRM1, DRD2) and body fatness in the children and mothers. Specifically, we are interested in data on BMI waist circumference and body fatness at all available time points within the ALSPAC cohort. Our analyses will determine the extent to which OPRM1 and DRD2 genotypes are associated with these variables, both cross-sectionally and longitudinally.