AceShowbiz - Fans know that deep histories of each family on "Riverdale" play a big role in the story. And in episode 4 of The CW's series season 4, the dark secret of the Blossoms was revealed that led to a shocking incest plot twist.

The episode, titled "The Midnight Club", saw the young characters going back to the past to when their parents were in high schools. It featured one of the most surprising confessions from Penelope. She admitted that she was adopted by the Blossom family for her red hair from an orphan from the Sisters of Quiet Mercy.

What's more shocking was that she'd been groomed by the Blossoms to become the "sister-companion" to Clifford, whom she ended up marrying when they grew up. Her friends were beyond suprised by the confession, labelling their action as some sort of incest.

The revelation further sparked speculation that Cheryl was adopted, which explained why her parents were harsher on her while being favourable toward her brother Jason. Judging by how Jason and Cheryl were close to each other, fans also believed that Cheryl were also planned to be the "sister-companion" to Jason though the latter found himself getting head over heels for Polly Cooper.