What attracts people to each other, is finding things in common.

We all do this, of course.

You meet someone. Introduce yourself. And then what do you do?

You starting asking each other questions looking for something in common.

It could be anything. Schools attended, hometowns, religion, number of siblings, vocation of relatives, hobbies, places traveled, etc.

The more common ground you find here, the more you will – generally – get along with each other and enjoy each other’s company.

Of course, this idea can be used to your advantage as well.

Say you are interviewing for a job.

If you dress like the CEO, talk like the CEO, and go to the same gym and church as the CEO – you would certainly be ahead of everyone else with fewer similarities.

As both researchers and compliance professionals know, there are several, and one of the most influential is similarity. We like people who are similar to us. This fact seems to hold true whether the similarity is in the area of opinions, personality traits, background, or life-style. Consequently, those who wish to be liked in order to increase our compliance can accomplish that purpose by appearing similar to us in any of a wide variety of ways.

-Robert Cialdini, Influence

The exception to this rule is something called “negging” in the language of so-called pickup artists. The idea is to say something subversively negative (negging)—but not too negative—to a woman to make her less confident. For example, the man might walk up to the woman and ask, “Did you just get your hair done?” Notice that it isn’t a compliment and it isn’t an insult. But the woman will register it as a criticism because there was no compliment appended to the question. The normal structure of that question would be “Did you do something with your hair today? It looks great.” When you put the compliment in the question, you’re using the “nice” strategy that won’t get you far. When you leave out the compliment and ask if the hair is different today, it suggests that perhaps you are not crazy about it. That unspoken put-down causes some women (not all, obviously) to reframe their situation as a confident male talking to a woman with some unspoken defect. That creates the illusion—or at least the possibility—that the man is a higher social rank. The perceived difference in social rank—illusion though it is—triggers attraction in the woman in this example because we are biologically wired to believe that people of higher rank probably have some sort of genetic advantage that got them there. And we want to mate with those people to pass those genes to the kids.