I remember during "doppelgänger week" in 2010 before I got into lifting and tanning, I changed my profile picture to Ed Helms (Andy from The Office/Dr. F****t from The Hangover) and everyone was like "omg! You look like a young version of him!"

I think it's the eye-wrinkles, dimples and massive teeth.
My sister on the other hand (pictured above) always gets told she looks like Lara Bingle.