Kissing & DNA
Kisses are taste tests for your bodies to figure out if the person you are kissing is a strong genetic fit with your DNA.
If you and the person you kiss are resistant to the same diseases you will not find each other attractive on a chemical/sexual level. The reason being if you were to make children together, your babies wouldn’t be as genetically strong as compared to you pairing up with someone who was resistant to different diseases as you. Put simply, if every person was resistant to 50 different diseases, your children would have a better chance at survival if you met someone with a different fifty than you (totalling a resistance to 100 diseases).
This is also often why one partner will come down with a cold/flu/illness and their partner won’t catch it- they are resistant to the disease and that’s part of why they are unconsciously attracted to each other.
Fifty-nine percent of men and 66 percent of women say they have ended a budding relationship because of a bad kiss. It turns out that our sense of smell may be partially responsible as we pick up subconscious clues about the other person’s DNA or reproductive status. Biologist Claus Wedekind found that women are most attracted to the scent of men who have a very different genetic code immune system than their own in a region known as the major histocompatibility complex. This may be because potential children would have a higher level of genetic diversity, making them healthier and more likely to survive.
Here’s also a PBS short that touches on some of Kirshenbaum’s ideas, courtesy of Brain Pickings. Though the most fascinating thing of all this to me is this use of kissing to sniff out the best genetic match/immunity compatibility.