Why is yoda so short

Yes it is his race that is short, his race are also cousins to the wookies who are massive.

Two reasons. One is his race, which is naturally short, obviously. Another is, well, u know how older people get shorter? He IS circa 900 years old... so... yeah.

because he is deformed !!!!! lol!!!!!

its the species of alien he is there are others like him that once served on the council and still do

its yodas species the only other one of his species i know is yaddle (look on wookipedia)

Because that's how big the puppet was! lol

Maybe he had a growth stunt at a very young and hasn't grown an inch since (Lol).

The real answer? Cuz George Lucas wanted somebody who was the opposite of Obi-Wan, so instead of a tall human, he used a short alien.