Her mother, Alice Cooper, had a baby in high school and gave him up for adoption.
Now, finally, season 2 will delve deeper into the storyline of the mysterious brother, TV Line reports.
Chic Cooper - that's his name btw - will show up in the middle of the season, and will become a reoccurring guest star.
So who could be playing the brother?
Naturally, fans have their theories. A popular Reddit theory is that Betty's brother is Joaquin, Kevin's Serpent (ex) boyfriend... but now that we know his name is Chic, he will definitely be new to the show.
There was also a theory going around that PLL's Caleb (Tyler Blackburn) was coming to the show to play the brother.
We guess we're just going to have to wait and see! Riverdale season two comes back October 11!