Since your last birthday, a lot of things have changed. For one, you're much smarter than you were last year. That's obvious.

But there might have been some other changes — ones that you weren't ready for. Perhaps you've sprouted several inches above everyone else in class. Or maybe they all did the sprouting and you feel too short.

Maybe you haven't gained a pound and you feel like a feather on the seesaw, or maybe you can't fit into your favorite pair of jeans. And now you're looking in the mirror, thinking only one thing: Am I normal?

Everybody's Different

First of all, what's normal? There's no one type of normal. The next time you go to the mall or a sporting event, take a look around. You'll see tall people, short people, and people with broad shoulders, little feet, big stomachs, long fingers, stubby legs, and skinny arms ... you get the idea.

You can change your hairstyle or put on a new hat, but the way you look isn't entirely under your control. Your looks were largely determined by your parents. When your parents created you, they passed on their genes, which helped to decide your size and shape, your eye color and hair texture, even whether you have freckles.

Small or Tall

Height is just one of the thousands of features your genes decide. In fact, because you have two parents, your genes act like a referee, giving you a height that usually lands somewhere between the height of each parent. If both your parents are tall, then most likely you will be tall too. But if you have questions about how tall you're going to be, ask your doctor to help you figure it out.

But genes don't decide everything. For example, eating an unhealthy diet can keep you from growing to your full potential. Getting plenty of sleep, enough exercise, and nutrients will help you grow just like you should.

No doubt you're wondering how fast you should grow. It depends. There's no perfect or right amount. On average, kids grow about 2 inches (6 centimeters) a year between age 3 and when they start puberty (when your body starts changing and becoming more grown up).

Your doctor will know how your growth has been going over the years. Two centimeters here and 2 inches there are not nearly as important as the height you're at now, how you've been growing up to this point, and what other changes your body may be going through.

Growth Spurts

Have you grown a lot in a very short time? Everyone has a growth spurt during puberty. The average age for starting puberty is about 10 for girls and about 11 for boys. But it can be earlier or later — between 7 and 13 for girls and 9 and 15 for boys.

You'll usually begin to notice that you're growing faster about a year or so after your body starts to show the first changes of puberty — girls will develop breasts and a boy's penis and testicles will get bigger.

Weighing In

Weight can vary a lot from kid to kid. It's tempting to compare yourself with your friends. But kids often weigh more or less than their friends and are still considered to be at a normal weight. TV and magazines might make us think our bodies should weigh and look a certain way. But in real life, there are a lot of differences. The best way to have a healthy weight is to eat right and get a lot of playtime (exercise).

What to Do if You're Worried

If you have concerns about how you look  — or how your body is changing — talk it over with your  parents or your doctor. The doctor can tell you if anything is wrong.

But most likely, your one-of-a-kind body is growing just like it's supposed to.