Dog Talk: From the tiny Chihuahua to the gigantic Great Dane

What heights will these puppies grow to? Some people say its diet that determines their growth. Others say its the genes or the environment. -- Filepic

Does size matter? For dog owners, the answer is usually yes. Looking after a little dog that stands ankle-high is quite a different prospect than adopting one that can look a small pony in the eye.

In the past, nobody was really sure how to predict height. Some thought it was entirely genetic, that height is determined purely by the size of the parents. Others said it depended entirely on environment, like whether the puppies have enough to eat at various life stages. Still others argued it was a blend of the two.