Opposites may attract if they're magnets. But that's not so true when it comes to kisses.

Turns out that the appeal of a first kiss may have as much to do with familiar-to-you bacteria that live in your potential mate's mouth (over 20 billion reside there) as how he or she looks or acts.

Researchers in the Netherlands recently discovered that repeated episodes of intimate kissing (full tongue contact and saliva exchange) can transfer more than 80 million bacteria from one person to another, and make couples' oral biomes increasingly similar.

After a transfer, some bacteria come and go, but others stay for the long term, bonding the two mouths.

That could partly explain why some couples enjoy kissing each other: They feel good about the way the other tastes, and their bacteria get along!

Other studies show that a first kiss is more likely to affect your feelings of attraction (or disinterest) toward a potential mate than other "information." Perhaps it's the bacteria you bring to the first kiss that affects your desire to keep on kissing, or not.

Clearly, the more that's discovered about your microbiome - the bacteria in your intestine, your mouth and on your skin - the more important your choice of bacteria seems to be! So pucker up and see if a biome swap builds compatibility.

Maybe you really are made for each other!

Then you can enjoy all the benefits of a successful intimate relationship: reduced stress and  lower blood pressure.

© 2014 Michael Roizen, M.D. and Mehmet Oz, M.D.
Distributed by King Features Syndicate, Inc.