There are celebs we know are twins, like Tia and Tamera, and then there are those we had no idea shared the womb with a sibling. Check out the list of celebs who we were shocked to learn are part of a set.

Not only does Scarlett Johansson have a twin brother named Hunter who — go figure! — is pretty darn cute, but she's actually shared screen time with her twin bro! Well, they were in the same movie, at least. In 1996's Manny & Lo, Scarlett played Amanda while Hunter had a bit part as a member of the "Golf Cart Family." But, hey, People magazine did dub him a hot bachelor in its "Single and Sexy Men of 2008" feature.

These poor girls' parents! With all the boys that must have come a-knocking on their door during Gisele and Patricia's high-school years, we doubt Mom and Pop Bundchen ever got any shuteye. While Gisele reportedly was jealous of her "hotter" sister when they were younger, Patricia no longer models. Instead, she acts as her supermodel sis' PR manager!

If he ever needs a stand-in for one of his movie roles, Jon Heder has an unrivaled one in identical twin brother Dan. And by identical, we mean identical — we can't even tell them apart in pictures. "We caused a lot of trouble by pretending to be each other," Jon joked to David Letterman. "The memories still give me a good chuckle." Fun fact: Dan acted as an animator on the kids' movie Monster House.

Alanis has put out some pretty angry albums in the past, but maybe her newer, happier stuff is thanks in part to some Zen tips from her twinsie, Wade. Also a singer, Alanis' twin serves as a spokesman for lululemon athletica apparel — through which he discovered his love for yoga. In 2005, he even joined the lululemon Yoga Pilgrimage and toured to promote his own album.