Men can pass some of their genetic code to women while kissing, reveals study.
The DNA will hang around in their mouth for at least an hour even after a brief encounter.
This suggests that women's saliva could reveal evidence of unwanted attention in cases of assault, or even telltale signs of infidelity, according to the New Scientist.
Natalia Kamodyova and her colleagues at Comenius University in Bratislava, Slovakia, asked 12 couples to kiss each other passionately for at least 2 minutes. Saliva samples were then collected from the women at 5, 10, 30 and 60-minute intervals.
Kamodyova's method can only be used to identify a man's DNA in a woman's saliva as it relies on detection of the Y chromosome.
The results show that the man's DNA was still present and could be detected through amplification after at least an hour, and possibly longer.
This study have shown that it's possible to get a full profile of the kisser, which could be useful in crime investigation to pinpoint the possible perpetrator among suspects or exclude those innocent, said Kamodyova.
Her team is now investigating whether the DNA survives longer than an hour and whether it's obtainable from the mouths of women who have died