Is your ring finger longer than your index finger? You might be a Builder. Are you a Democrat? So are many Explorers. Negotiators are skilled at emotional expression and dealing with people, and Directors are competitive and want to be the top dog. Says who? Says Helen Fisher, a biological anthropologist who has been studying love and personalities 30 years. Through a questionnaire of 40,000 people she created for Chemistry.com, she concluded there are four predominant personality types and that genetic traits determine the types. "I’ve written five books; I’ve worked on love for over 30 years, and I finally understand people ... on a level I never thought I would,” she said. "I also understand why various relationships just never end up really working.” In her latest book, "Why Him? Why Her?,” Fisher reveals the results of her two most recent studies. One defines personality types and the other describes the nuances of romantic relationships between people of different and the same personality types. But before you can analyze your relationship based on your personality type, you have to learn what type you are. Your personality type, Fisher says, has everything to do with your brain chemistry. In Builders, serotonin is more prevalent. Explorers show higher levels of dopamine. Estrogen and testosterone influence the personality traits of Negotiators and Directors, respectively. "What was surprising was how real these patterns are,” Fisher said. Through an ongoing study of saliva and urine, she’s finding consistency with the personality types and the predominant brain chemicals that influence them. Fisher says personality is made of two major components: biology and character, much like nature and nurture. Your temperament is the biology or nature side of your personality — those traits you inherited from your parents such as curiosity, aggressiveness and stubbornness. Your character is everything you’ve gained from experiences — the "nurture” side of your personality. Fisher found by analyzing profiles on Chemistry.com that each personality type tends to use certain words more often in its self-descriptions. Explorers favor the word "adventure.” Builders use "family” most often. Directors like "intellectual,” and Negotiators love "passion.” Learning your type can help you understand your strengths and your weaknesses and can ultimately help you function better in your relationships. Go online to www.Chemistry.com to take Fisher’s quiz or just read the following descriptions to find out what type you are.