How can vampires in twilight have 25 chromosomes when they don't have blood?

because its not real!

It's just Stephenie Meyer's way of explaining why Renesme grows like she does. Since vampires don't grow and humans grow normally, Renesme should grow slower than most babies, right? Well Meyer says that vampires have 25 and humans have 23 that means Renesme has 24, which is the same number as a werewolf so she grows like a werewolf. It doesn't make sense. At all. But it's Twilight, what can we do?