Speculations on Nathan's (Martin Henderson) true identity in "Grey's Anatomy" get wilder and wilder, as fans wait for the long-running ABC series to return in February. This time, some posit that the New Zealander is actually a transgender and he is Owen's (Kevin McKidd) sister.

As debates on why the redheaded doctor hates Nathan continue, many fans concoct plotlines on how creator Shonda Rhimes will divulge the two's connection. Rumors that Nathan is Owen's brother-in-law has so far been the most feasible among the list. The fact that Owen's sister was mentioned during the doctor's heart to heart talk with Meredith (Ellen Pompeo) last midseason finale seems to suggest that this may be the case. It is possible that the woman died and Owen blamed Nathan for what happened.

Viewers also saw Owen's mother visiting her son in Grey Sloan Memorial Hospital and encountering Nathan. She embraced him as if he was her long-lost kid. Nathan called her "Mother." This suggests that at one point in their life, Owen and Nathan considered each other family. This time, though, a wild assumption posits that Nathan was once a woman, Owen's sister in fact, and underwent the knife to become who he is right now.

Ask Ausiello of TV Line reports, however, that the transgender storyline is "highly unlikely." Nathan is confirmed to be from New Zealand, while Owen was born and raised in Seattle. Ausiello said that when Rhimes offered the job to Henderson, she even asked him to retain his accent. He said that "bigger mystery" about the Nathan-Owen plot was whether Owen's sister was still alive.

Meanwhile, Rhimes talked to Entertainment Weekly about the midseason premiere and how it would be the perfect start for the series in 2016.

"We've been having a blast. The first episode that comes back is extraordinary and very, very powerful, and directed by Denzel Washington. It certainly puts us on a path for the beginning of the second half of the season," she shared.

"Grey's Anatomy" season 12 will return on Feb. 11 at 8 p.m. EST on ABC.