The Big Bang Theory Season Finale Twist Could Lead to Leonard and Sheldon Becoming Brothers

The Big Bang Theory is bringing in Leonard's father for the season finale this week, and it could have major repercussions for the series, especially two characters on it.

When Alfred, Leonard's dad played by Judd Hirsch comes to visit for the wedding, he and Leonard's mom Beverly have "so much tension that even Sheldon picks up on it," EP Steve Molaro told EW. However, another mother connects well with Alfred - Sheldon's mom Mary, played by Laurie Metcalf.

"An unexpected attraction springs up between" them over their "shared dislike of Beverly and a genuine fondness of each other," Morlaro teased. Yes, if those two got together, that would have brotherly consequences for Leonard and Sheldon.

The Big Bang Theory season 9 finale, "The Convergence Convergence" airs Thursday at 8pm on CBS.