I don't know how they would react if they found out they were step-siblings in some way. I mean, that's what they would be right? It didn't stop the MC going for Nikki/Cara, but that didn't have any blood ties like Layla and Lexi could have. I don't doubt it is him though. Everybody already knows everybody else in Madison Springs, who why not throw another monkey in the wrench and bring the MC's real father in as Layla's and Lexi's.
Would Layla or Lexi stay with the MC, or better yet, would their parents let them stay together. Then his mother would find out if her and Adriana got together, oh boy.
Ugly clusterfuck possibly incoming.