NEW YORK — Looking for love? Try leaning in for a … cheek swab.

A couple of genetic testing companies are promising to match couples based on the DNA testing, touting the benefits of biological compatibility.

The companies claim that a better biological match will mean better sex, less cheating, longer-lasting love and perhaps even healthier children.

"How many dating services can you think of where they can suggest you might have better children?" said Eric Holzle, founder of ScientificMatch.com, one of the first online dating sites to use DNA.

Holzle wouldn't reveal membership numbers, but GenePartner, a Swiss company that works with matchmakers and dating sites, has tested more than 1,000 people, according to chief scientific officer Tamara Brown. Some were already coupled and took the test out of curiosity.

The GenePartner Test is $99, and will be offered at the dating site sense2love.com when it relaunches next month.

The idea is that people tend to be attracted to those who have immune system genes that are dissimilar from their own.

Biologists say the HLA genes of the immune system — which are responsible for recognizing and marking foreign cells such as viruses so other parts of the immune system can attack them — also determine body odor "fingerprints." And people tend to be attracted to the natural body odors of those who have different HLA genes from their own.

In one study, Swiss biologist Claus Wedekind found that women who were not taking hormonal contraception preferred the natural scent of men whose immune systems were the most different from theirs.

But don't put too much faith in this, experts said.

Dr. Rocio Moran, medical director of the General Genetics Clinic at the Cleveland Clinic, called the idea "ridiculous," and said the science of attraction is too complex to look at only a few genes.

"They are just trying to make a buck," she said. "That if it's genetic, it must be real science."

When a random sample of married people was studied, their immune systems were not that different, said Patrick Markey, associate professor of psychology at Villanova. And he notes that hundreds of studies have shown the importance of personality and physical appearance in choosing a mate.

For some, factors such as whether the person smokes, is fat or wants children will override biological compatibility, said Helen Fisher, a biological anthropologist and author of "Why Him? Why Her?" She believes genes play a role but said it's only one part of the puzzle.