Project DNA

 (DNA being short for Do Not Assume) was the central twist of Big Brother 5. This twists involved two sets of siblings in the House.
 * Michael "Cowboy" Ellis and Jennifer "Nakomis" Dedmon were estranged siblings who were unaware of each other before the airing of the show and revealed it to the rest of the House Guests during week 2.
 * Adria Klein and Natalie Carroll were identical twins and would swap places every few days. If the two made it to week 5 without being discovered, they would both enter the game as individuals.
 * Andrew Daniel and Diane Henry also revealed that they both had twins, but their twins were not competing in the game.