A 18-month-old girl from urban Delhi is brought to the pediatric clinic for routine assessment. Her weight is 9.5 kg (10th percentile), height is 75 cm (5th percentile), and head circumference is 45 cm (3rd percentile). She has normal developmental milestones and no dysmorphic features. Laboratory investigations (hemoglobin, blood glucose, thyroid function) are normal. Her parents are both of short stature (father 160 cm, mother 155 cm). What is the most appropriate next step in management?