When answering this question, you can compare the reasons why younger and older people might smile more. For example, you could say that children and young people tend to smile more because they are carefree, easily amused, and less burdened by responsibilities. On the other hand, older people might smile less due to stress, life challenges, or health issues, but some older people may smile more because they have learned to appreciate life and find joy in small things. You can also mention that smiling habits can vary depending on personality and cultural background.