BIOLOGY: Builders tend to have higher levels of serotonin, a brain chemical known for instilling calm.
IDEAL MATE: A fellow Builder, who appreciates crucial details like alphabetizing the owner's manuals for appliances dating back to 1987.
OUR FAVORITE COUPLE: Paul Newman and Joanne Woodward, whose marriage lasted for 50 years. In Hollywood, no less.
BIOLOGY: Explorers have high levels of dopamine, a chemical in the brain associated with feelings of euphoria and optimism. Explorers love sex. Love.
IDEAL MATE: A fellow Explorer. In short, a partner who won't flinch if you ask him to play hooky and go to Bangkok on a whim.
OUR FAVORITE COUPLE: Duh. Brad and Angelina, the jet-setting, tattooed, unwed parents of six.
BIOLOGY: In the womb, the Negotiator was exposed to high levels of estrogen, the hormone associated with sensitivity and intuition.
IDEAL MATE: A Director — because two Negotiators who can't stop saying "I love you" to each other would make anyone want to barf.
OUR FAVORITE COUPLE: Kate Winslet, the Negotiator, emotes for a living, while Director Sam Mendes literally, um, directs.
BIOLOGY: In the womb, the Director was exposed to a high level of testosterone, the hormone associated with competitiveness and aggression.
IDEAL MATE: The Negotiator (at right), who brings love and affection to a Director's analytical life.
OUR FAVORITE COUPLE: Reese Witherspoon and Jake Gyllenhaal. She named her company Type A Films; he's the doe-eyed boy with the strong shoulder to cry on.