The actor of Joaquin himself, Rob Raco basically confirmed it on Twitter...
However, Lili Reinhart has come and denied that specific rumour, however she has basically confirmed one part of it.
While speaking to Seventeen, Lili revealed that, "I feel like I want to shut that theory down," she said.
"Maybe there was a romance between Alice and F.P., but Joaquín went on that bus to San Junipero and he's just going, sadly for Kevin. But you know what? I think that was for the benefit of my sweet little Kevin."
Okay, so Joaquin is probably not the brother, BUT it looks like something between Alice and FP definitely went down in the past.
It doesn't rule out that Betty's brother could be her and Jughead's half-brother... Yikes.
We know, gross, but the show has totally dabbled in incest before (Polly Cooper and Jason Blossom are cousins, and she is having his baby...)
And, if the couple did end up sharing a sibling, it would just add to the tension that is building between them for season 2.
We already know that Jughead becoming one of the Southside Serpents is going to get in the way of their relationship for a while, as well as new character Toni Topaz turning their love into a love triangle... but Lili confirmed that when they found out that the show was renewed for another season, they wanted #Bughead to suffer.
"But since we did get a second season, we wanted to keep the drama going," she continued to Seventeen.
"We kept Jughead at Southside High because we didn't want to give them a happily ever after just yet."
We think sharing a sibling could totally assist with that. #DramaLlama.