When your spouse does things that mystify you or drive you crazy, you probably wish he/she would behave more reasonably. Yet your partner may not be “programmed” to behave any other way.

My research suggests that each of us has a “love personality”—how we are naturally inclined to behave with a romantic partner—that may depend on the particular chemicals dominant in one’s brain. This research comes from my analysis of existing genetic and pharmaceutical studies, as well as from my work as chief scientific adviser to the Internet dating site Chemistry.com. I devised a series of questions to establish to what degree we express specific chemicals in the brain and collected data on 28,000 men and women.

I determined that love personalities can be divided into four main types, based on which brain chemicals—sero­tonin, dopamine, estrogen and testosterone—are predominant. Some people show characteristics of one type…others are a combination. The four types…


Serotonin promotes orderly, cautious behavior and respect for authority. More than the other three types, Builders enjoy planning far ahead. They are literal and predictable, fastidious about their possessions, conscientious and dutiful. They tolerate routine well.

What the Builder brings to a relationship: Builders are good at forming strong networks and run businesses and households with great efficiency. A Builder will never keep you waiting, forget to fill the gas tank or write down the wrong flight departure time.

Sources of stress: Builders are stubborn—if you helpfully suggest to a Builder a better way to mop the floor, you may find yourself in an argument. Builders can be moralistic and overly rule-bound. They are suspicious of new experiences and ideas—in fact, they will be quick to point out all the reasons why an idea might not work.

Sex and fidelity: Builders are most likely to be attracted to other Builders. They are serious when they court. Sex may become routine, but Builders like routines, and two Builders will rarely fight about their life in the bedroom. Highly loyal, Builders are unlikely even to consider divorce.

Living with a Builder: Let the Builder do things his/her way, even if you’re convinced there is a better way. If you crave more adventure than the Builder, map out a new experience beforehand so that it doesn’t look like a risk…or let the Builder plan the details.


High dopamine activity is associated with curiosity, spontaneity, risk-taking, novelty-seeking, irreverence, mental flexibility and optimism.

What the Explorer brings to a relationship: Explorers are enthusiastic and full of energy. Charming and creative, Explorers don’t like to be told what to do—they chafe at rules, plans and schedules. They can be extravagant gift givers.

Sources of stress: The Explorer’s impulsiveness can grate on someone who would like to know what time ­to be ready for dinner or who prefers to buy theater tickets in advance. An Explorer doesn’t like repetitive tasks, so you shouldn’t depend on an Explorer to take out the garbage every night.

Sex and fidelity: Explorers tend to be attracted to other Explorers, and they make exciting sex partners. Instead of discussing the deep meaning of a relationship, an Explorer would rather make love or go out together for a good time. Big fights may be followed by passionate lovemaking. It is important to have adventures with an Explorer, lest he/she decide to find someone else to share his experiences with.

Living with an Explorer: Don’t try to keep an Explorer from doing what interests him. Instead of imposing rules, find parameters that the Explorer can live with.

Example: A Builder husband and Explorer wife had repeated showdowns over the Explorer’s chronic lateness. They finally agreed that the Explorer would call her husband when she was running late…and that the Builder would go ahead with plans instead of waiting for his wife, who would join him later.


Men, as well as women, can have high estrogen activity in the brain, promoting connection-seeking.

What the Negotiator brings to a relationship: Negotiators are highly verbal, agreeable and good at reading people. They are skilled at coming up with the right thing to say to make others feel valued. Negotiators have rich imaginations and think holistically—they see creative and unusual connections between disparate pieces of information. They are flexible and willing to change their minds.

Sources of stress: The ability to see many sides of an issue can make it difficult for Negotiators to reach decisions. They are so imaginative about possibilities that they may create constant anxiety for themselves. Because Negotiators want everyone to be happy, they don’t always say clearly what they need or mean, leading to confusion and misunderstanding.

Sex and fidelity: Negotiators tend to be most attracted to Directors (see below). The Negotiator needs the Director’s logic, forthrightness and decisiveness to get things done.

Negotiators seek deep intimacy with their partners—they want a soul mate—so they will be patient, forgiving and compassionate. But if a Negotiator feels that he/she won’t ever “reach” you to share an intimate life together, he may eventually turn elsewhere for the romance he craves.

Living with a Negotiator: Recognize that what sounds to you like endless processing is a way for the Negotiator to address the needs of everyone involved. Don’t rush the Negotiator’s decision. Trust that once he has examined all the angles, the solution will make a lot of people happy, including you.


Both women and men can have high testosterone activity in the brain, leading them to be competitive, straight-forward, logical and pragmatic.

What the Director brings to a relationship: You don’t have to second-guess Directors—they say what they mean without nuance. Because of their ambition and competitiveness, they are dedicated to their work and typically well-paid. Directors like to focus very deeply on a few subjects and learn everything about them.

Sources of stress: Directors can alienate people with their bluntness, coming across as dictatorial and aloof. They get impatient when others are not as focused as they are or don’t immediately grasp their ideas. They have a hard time leaving work behind—at the beach, the Director is the one checking e-mail.

Sex and fidelity: Directors are most likely to be attracted to Negotiators. The Director relies on the Negotiator’s people skills. Sex is a genuine form of intimacy for them. They tend to be loyal, but if they cannot get the physical connectedness they need, they will seek it elsewhere.

Living with a Director: Don’t give a Director hints or make gentle requests­—the message will not get through. Instead of “Would you have time to…” say, “I need you to do this by Friday.” During disagreements, appeal to logic (“This would be more efficient”) rather than emotion (“This makes me frustrated”).

To get Directors to relax outside work hours, encourage activities that are absorbing, challenging or competitive enough to distract them, such as joining a tennis league or a book club.