Have you ever known a married couple that just didn't seem as though they should fit together -- yet they are both happy in the marriage, and you can't figure out why?

I know of one couple: He is a burly ex-athlete who, in addition to being a successful salesman, coaches Little League, is active in his Rotary Club and plays golf every Saturday with friends. Meanwhile, his wife is petite, quiet and a complete homebody. She doesn't even like to go out to dinner.

What mysterious force drives us into the arms of one person, while pushing us away from another who might appear equally desirable to any unbiased observer?

Of the many factors influencing our idea of the perfect mate, one of the most telling, according to John Money, professor emeritus of medical psychology and pediatrics at Johns Hopkins University, is what he calls our "love map" -- a group of messages encoded in our brains that describes our likes and dislikes. It shows our preferences in hair and eye color, in voice, smell, body build. It also records the kind of personality that appeals to us, whether it's the warm and friendly type or the strong, silent type.

In short, we fall for and pursue those people who most clearly fit our love map. And this love map is largely determined in childhood. By age eight, the pattern for our ideal mate has already begun to float around in our brains.

When I lecture, I often ask couples in the audience what drew them to their dates or mates. Answers range from "She's strong and independent" and "I go for redheads" to "I love his sense of humor" and "That crooked smile, that's what did it."

I believe what they say. But I also know that if I were to ask those same men and women to describe their mothers, there would be many similarities between their ideal mates and their moms. Yes, our mothers -- the first real love of our lives -- write a significant portion of our love map.

When we're little, our mother is the center of our attention, and we are the center of hers. So our mother's characteristics leave an indelible impression, and we are forever after attracted to people with her facial features, body type, personality, even sense of humor. If our mother was warm and giving, as adults we tend to be attracted to people who are warm and giving. If our mother was strong and even-tempered, we are going to be attracted to a fair-minded strength in our mates.

The mother has an additional influence on her sons: she not only gives them clues to what they will find attractive in a mate, but also affects how they feel about women in general. So if she is warm and nice, her sons are going to think that's the way women are. They will likely grow up warm and responsive lovers and also be cooperative around the house.

Conversely, a mother who has a depressive personality, and is sometimes friendly but then suddenly turns cold and rejecting, may raise a man who becomes a "dance-away lover." Because he's been so scared about love from his mother, he is afraid of commitment and may pull away from a girlfriend for this reason.