.. And your question is??
Height is determined by genetics. Even though your sister is younger than you .. You both are still not finished growing yet.
My little sister is taller than me 5'8 and I'm only 5'3?
What's your question? My little sister and I were born 2 years apart (oddly enough, we have the same birthday....) She is a lot bigger than me and I'm older.. There isn't anything wrong with it of that's what you mean. Height has nothing to do with age ;)
You don't mention your age or your gender, but people grow at different rates. I am an average height for a woman (5'5"), but I was taller than all my friends in the fifth grade ... Just finished growing early.
Some siblings are taller than one another. I'm taller than my older sister and my mom.
So you got the short gene and she got the tall one. It happens. My dad had 3 brothers. Dad is the oldest and is 5'7", Russell 5' 9", Roger 5'5" and Joel, 6'1". My grandfather was 6'0". Just goes to show, it is all the luck of the draw.