GP Dr Janet Menage is collecting height and weight data on dogs and their owners to test the hypothesis that the home environment rather than genes determines obesity. Dr Menage aims to compare the BMIs of at least 100 'human:dog units'. 'Dogs who are overweight like their owners do not share genes but they do share a similar home environment,' she said. Dr Menage and her Sheltie Tiger, (left), have a BMI of 22, while Jessie (right) has a BMI of 26. To participate, email firstname.lastname@example.org.