Efren landed his breakthrough role playing lovable sidekick Pedro Sanchez in Napoleon Dynamite, but his sibling Carlos claims the hit 2004 comedy created a rift between the pair.
Carlos tells Tmz.com the trouble started when he began helping Efren out by impersonating the busy star at promotional gigs, but admits he crossed the line when he made a press appearance without his brother's permission.
They fell out and in 2008, Efren sent Carlos a cease-and-desist letter urging him to stop "interfering with (Efren's) personal and professional life".
Now Carlos admits he and Efren no longer speak: "I did attend an event without his knowledge as I was being immature and wanted to get back at him for a personal matter... I think it's safe to say the magnitude of Napoleon Dynamite and everything that has come along with it has ruined my relationship with my twin."
However, Carlos hopes to one day make amends, adding, "I would love to talk to Efren. Maybe even work together in the future. His support would be amazing."
A spokesperson for Efren says, "Efren prefers to keep what's between he and Carlos, between he and Carlos."