Board Thread:Boruto Discussions/@comment-31847914-20170427062624/@comment-734582-20170427074658

Considering a 10-chapter manga was dedicated to Shin, the synthetic humans, the existence of Mitsuki as a synthetic human with his own one-shot manga, i think it's logical that Kawaki has at least some synthetic or augmented part.

I don't think he was made by Orochimaru, i think it's more likely that he either got an Otsutsuki's power (IE the power-absorbtion part like Momoshiki had) or he stole Orochimaru's research to enhance himself.