Zoya's kids

Zoya said on the show that she was currently 25 years old, and her sister left or died (I don't remember which) when she was 9, so 16 years ago. And Zoya's oldest 3 kids are her sister's kids. But the boy looks only about 10 years old, so how can that be? He's definitely not 16 years old. Am I misunderstanding something?

I dont understand her family thng