Separated At Birth
My nephew Ryan looks a lot like Sean Rogan. I'm not the only one who thinks so. When the 40-Year-Old Virgin was first released, Ryan's friends and co-workers started calling him Cal, the character played by Rogan. Now that Rogan is starring as Ben in Knocked Up, I expect Ryan to have people start calling him Ben. The pictures (of Rogan, below, and Ryan, right) don't tell the entire story. 
Ryan talks a lot like the characters played by Rogan, has the same chunky build and has a similar goofy demeanor, not to mention that his love of Star Wars and video games also connects him to the characters played by Rogan.