For better or worse, volleyball is one of those sports that does place some emphasis on genetics. If you're not very tall, though, don't quit before you even start. Shorter players may not be the best blockers on the team, but they can be stellar servers and quick on their feet. A lack of height will not rule you out.
On the other hand, if you're a taller athlete who prefers a different sport, consider giving volleyball a shot. You may find your height makes you a natural, and you never know if you'll fall in love with a sport unless you try.