FX's new series Taboo (Tuesdays at 10/9c) follows James Keziah Delaney, a man who was presumed to be dead but returns home to London in 1814 to lay claim to his father's shipping empire.
I don't know how long the character was away, but that set up makes it possible for this to involve Genetic Sexual Attraction.
The show is full of twists, but perhaps the biggest is that a major ongoing story arc involves an incestuous relationship between James and his married half-sister Zilpha, played by Oona Chaplin. And apparently we're supposed to root for it even knowing their blood relation.
We don't endorse cheating on this blog. However, not all marriages are closed. If her marriage is open or if it ends, heck yes root for them.

"My objective is to get people that watch the show dying for us to get into bed," Chaplin told TVGuide.com with mostly a straight face. "That's my objective. And I think that was a common objective of the team, so if people want a brother and a sister to get it on like there's no tomorrow, then we won."
Then have her marriage end or make sure it is established to be open. We appreciate the objective of giving people a look into consanguinamorous attractions.
Taboo airs Tuesdays at 10/9c on FX.