From ET Canada:

Why Ari Millen Is A Canadian To Watch
Ari Millen was an easy choice to include in our Canadians To Watch In 2015 Week, because you’re going to be seeing a LOT of him this year! The actor joined “Orphan Black” in Season 2, but the big reveal of the season finale was that he is a male clone!

Ari only found out about the revelation two weeks before shooting the shocking twist. “I’m still coming to grips with it,” says Ari. “It is such a huge revelation, not only personally as an actor, but also on the show.” Continue reading.