Abigail Van Buren (L) and Ann Landers - advice columnists (Photo by Hulton Archive/Getty Images)
Ronde (L) and Tiki Barber - NFL players (Photo by Travis Lindquist/Getty Images)
Kristina (L) and Karissa Shannon - playmates (Photo by Tom Briglia /Getty Images)
Kristina (L) and Karissa Shannon (with Hugh Hefner) - playmates (Photo by Denise Truscello/WireImage)
Randy (L) and Jason Sklar - comedians (Photo by Noel Vasquez/Getty Images)
Daniel (L) and Henrik Sedin - NHL players (Photo by Jeff Vinnick/NHLI via Getty Images)
Paul (L) and Morgan Hamm - Olympic gymnasts (Photo by Jed Jacobsohn/Getty Images)
Ozzie ( L) and Jose Canseco - MLB players (Otto Greule /Allsport)
Nelson (L) and Eddy Angelil with mom Celine Dion (Photo by Ethan Miller/Getty Images)
Mary-Kate (L) and Ashley Olson - actresses (Photo by Kevin Mazur/Getty)
Tamera (L) and Tia Mowry - actresses (Photo by Arnold Turner/WireImage)
Barbara (L) and Jenna Bush - daughters of former President George W. Bush (Photo by Mario Tama/Getty Images)
Maurice and Robin Gibb - musicians, The Bee Gees (Michael Putland/Getty Images)
Marie Hendrix (L) and Gabrielle Vaudremer - oldest living twins at 101 (Photo by NICOLAS LAMBERT/AFP/Getty Images)
Jason (L) and Jeremy London - actors (Photo by Michael Bezjian/WireImage)
Mito (L) and Tracker - born using an IVF technique preventing genetic diseases (Photo by William F. Sutton/AFP/Getty Images)
Niza (L) and Nero - white lion babies (Photo by JOCHEN LUEBKE/AFP/Getty Images)
Aleut (L) and Gregor - at Nuremberg Zoo in Germany (Photo by Hans-Martin Issler/Getty Images)
Doug (L) and Derek Perry - DJ’s (Photo by Chelsea Lauren/WireImage)
Markieff (L) Marcus Morris - college basketball players (Photo by Ethan Miller/Getty Images)
Bob (L) and Mike Bryan - double’s tennis partners (Photo by GREG WOOD/AFP/Getty Images)
Po (L) and De De at Madrid’s Zoo (Photo by JAVIER SORIANO/AFP/Getty Images)
Twin baby orangutans - born at an enclosure at the Foundation for Sustainable Ecosystem in Medan, North Sumatra province (Photo by AFP/AFP/Getty Images)
Two rare Peninsular pronghorns twins born at the Los Angeles Zoo (Photo by David McNew/Getty Images)
Robin (L) and Brook Lopez - NBA players (Photo by Barry Gossage/NBAE via Getty Images)
Jason (L) and Jarron Collins - NBA players (Photo by Joe Murphy/NBAE via Getty Images)
Horace (L) and Harvey Grant - NBA players (Photo by TED MATHIAS/AFP/Getty Images)
Nikki Bella (L) and Brie Bella - WWE wrestlers (Photo by Frazer Harrison/Getty Images)