The following is an excerpt.
Kissing is a physically affectionate act of pressing the lips against someone or something. The act is commonly used to express a multitude of human emotions like love, respect and friendship. However, what is less obvious is that when two lovers share a passionate kiss, they are also swapping their bacteria, bodily fluids and parts of their genetic code.
View the original article here: Lovers Swap Genes While Kissing: DNA Lingers in the Mouth Even After a Light Peck