Jugo is from a clan that is known for constantly taking sage chakra into their bodies. When they can't control it they turn into monsters due to the imbalanced sage chakra.
As we all know the Juubi is a huge mass of chakra which is said to be limitless or at least unfathomable. The Juubi's chakra is made up of natural energy (which is used for sage mode).
I think that Jugo's clan and other curse marked people have a piece of the juubi's body.
As you can see they share many characteristics and their bodies are malleable like when jugo gave some of his body to heal sasuke's wound. They both have zetsu like qualities as well.