“The minute I done smelt her, I knew she was for me!”

“The alleles of my Major Histocompatibility Complex are completely opposite from yours,” might not sound like pillow talk, but it is the literal basis for the “chemistry” many couples have.

Two companies, Basisnote and Scientific Match, are developing technology to match couples based on the genetic components of the human immune system — and their odor.

Studies have linked odor to immune systems and shown that people are most likely to be attracted to the smells of those who have different histocompatibility genes than their own. While those who have similar immune systems tend to not be attracted to each others’ odors.

“The MHC helps signal whether I find someone attractive or not,” said August Hammerli of the Switzerland based Basisnote. “What we have developed is a saliva assay that measures a person’s MHC and how they might react to another individual’s MHC profile.”