Game of Thrones' Kit Harington and fiancee Rose Leslie are apparently distant cousins

Kit Harington and Rose Leslie are engaged ... and related? Photo / AP

A Game of Thrones fan has done a lot of investigating and figured out that newly-engaged Kit Harington and Rose Leslie are actually related.

Harington, who plays Jon Snow in the hit HBO show, confirmed his engagement to his former co-star in the UK's Times newspaper today.

While fans are totally on board with the happy couple's news, one of them did a little bit too much digging and found something a little ... off, in the pair's Wikipedia pages.

They took to twitter to point out the similarities in the stars' profiles saying: "Cool that Kit Harington and Rose Leslie are engaged but also they are related?"

It turns out Harington's eighth-great-grandfather was Charles II of England, whom Leslie is also a descendant of.

Fans were quick to draw parallels to the show's often talked-about and criticised plotlines involving incestuous relationships, with one saying, "Oops, Game of Thrones did it again".

I feel duty bound to reveal that Kit Harington and Rose Leslie are distant cousins. They're both descendants of Charles II. pic.twitter.com/q8ms4JjCwN

— Rebecca Rideal (@RebeccaRideal) September 27, 2017

It's a somewhat tenuous link, but one fans are far too excited about to overlook.

The happy couple, on the other hand, are busy enjoying their engagement after keeping their romance under wraps for years.

They placed an ad in the Times which reads: "Mr K.C. Harington and Miss R.E. Leslie. The engagement is announced between Kit, younger son of David and Deborah Harington of Worcesterhire, and Rose, middle daughter of Sebastian and Candy Leslie of Aberdeenshire."

The couple met on the set of Game of Thrones, on which they played onscreen lovers.