Only Smart People Get This Right! Can You?

Take a close look at the puzzle in the image:

📖 A man has 9 sons.
📖 Each son has a sister.

❓ How many people are in the family?

At first glance, many people rush to answer 19 or even 20, but the correct solution requires a little careful thinking. 🧐

🔍 The Secret Is Hidden in One Word