Our genetic makeup, which is stable across life, influences our health and can serve as an early risk indicator for various diseases. Precise genetic tests exist for single-gene diseases, but common and complex conditions like obesity result from the subtle effects of many genes. We use Polygenic Risk Scores (PRSs) to assess comprehensive genetic risk for diseases or traits, encompassing many (hundreds to millions of) genetic variants. For BMI, for which high values can present a significant health concern, a PRS containing 941 common genetic variants influencing adult BMI has been established using UK Biobank data. However, these genetic variants are identified in mostly adult populations (> 50 years), and their performance in other age groups has been less well established. The transition from normal to high BMI and its onset at various life stages, particularly from childhood to adulthood, remains complex and warrants deeper exploration.