Why do I feel like other people's and my relatives' children grow up so fast?

My younger brother came back to my parents' house, and his kids have really grown up a lot. When they first visited, they were babies, but now the eldest son is in his first year of high school and my younger daughter is in her first year of middle school. They've really grown up so much and have become wonderful children. The eldest son is already in his first year of high school and is building his own worldview. It's amazing to see that baby grow up so splendidly. My younger daughter is carefree and cheerful. Even though she's at an age where a middle school girl might be shy, she's incredibly bright. She also has a caring side💦💦 She even scolds me sometimes. I really feel like both of them are growing up so fast. I always feel like other people's children grow up quickly. I hope for a future where today's children can live happily. Japan's economy is also changing in many ways, and I always hope it moves in a positive direction. Because today's younger generation will be the active members of the next society.