The Donquixote family had traditionally been the rulers of Dressrosa. In the distant past, Tontatta were the native population. This leads me to believe that Doflamingo is a dwarf. However, this has already been predicted by others before.
The new spin I am adding is this:
The body Doflamingo has been shown in up until now, is actually Cora-san's body.
This explains why Law will never forget Doflamingo. It also explains how Doflamingo is able to survive decapitation. Furthermore it would fit perfectly with the Ito-Ito no mi.
Doflamingo is definitely a character that likes to show off. It would fit with his character to want to take over a more powerful, more impressive body than the one he was born with.
What do you guys think?