Why are the newer generations so tall? I'm taller than my grandmother and aunt. My great grandmother was 5'0'', and I'm already 5'3'', even though I'm only fifteen years old. My brother is taller than my dad, and he is seventeen years old.

Yes usually. Better diet, and less physical labor (although healthy exercise helps one grow taller). In the 19th century and before, Europeans were very short. Around 5 feet. Good diet, no malnutrition, helped each generation grow bigger. Nowadays, they're some of the tallest people in the world. Countries that have high malnutrition have short people.