Oh yes, we went there.
As loyal EastEnders viewers will know already, Kat Moon (Jessie Wallace) gave birth to twins in 1984 when she was only 14 years old.
But Kat only remembers the arrival of one of the children - her daughter Zoe Slater.
Checking the 1984 birth records, a nun who was present at the birth found an official note from Kat's previous visit which read: "February 1, 1984. Kathleen Slater, 14. Live births - 2. One girl and one boy."
As we all know, the little girl - Zoe - was raised by Kat’s parents, who told the rest of the family that she was their own biological daughter.
Hence the iconic “YOU AIN’T MY MUVVA” scene.
But, as Kat’s parents wanted to keep her little girl in the family, wouldn’t they have done the same with her little boy?
And, you know, wouldn’t it have made sense for them to give him to, say, Jean Slater?
At the moment, Stacey has a very mysterious key hanging around her neck.
In a new trailer, we’ve seen Jean ask her daughter where she got the key from - only for Stacey to tell her that Sean handed it over to her.
Cue a panicked Jean telling her daughter that she isn’t well and that she needs to DROP her obsession with that key.
Following her mum’s reaction, however, Stacey is more determined than ever to figure out what that key opens.
Is Sean actually Kat's son? Could the key have something to do with Sean's parentage? Could it open up a safety deposit box containing his original birth certificate?
And, most importantly of all, could we see Sean eventually return to the Square to shed light on the mystery surrounding the key?
Speaking back in 2013, actor Robert Kazinsky did predict that Sean could one day make a comeback to Albert Square.
"My good friend Dominic [Treadwell-Collins] did just take over running it and so I am pretty sure he will ask me to come back at some point.
“At the minute, it is not viable that I could come back for any length of time because I don't live in this country and I don't particularly want to pay tax here. I live in America and I have done for five years, but never say never," he commented to the Belfast Telegraph.
We’re kind of in love with this theory; after all, Sean and Zoe are about the same age - and Jean is VERY fond of her beloved Kathleen.
Plus it means that Sean could come back; always a big fat plus in our books.
This would all be the perfect fodder for Kat and Alfie’s spin-off show; after all, they’ll need some family drama to mix in with Mr Moon’s unfortunate brain tumour diagnosis.
What do you think? Let us know via Facebook or Twitter (@CloserOnline) now.