As if bedbugs weren’t gross enough already, entomologists have now found that they get ahead by mating with their own mothers, brothers, sisters and fathers. By inbreeding, a single pregnant female can start the infestation of an entire building on her own.

Parent-sibling matings and sibling-sibling matings are rare in the animal kingdom. So this study reveals an exception to the anti-inbreeding rule. But I’m drawn to the report for a pettier reason. As far as I’m concerned, DNA evidence has trumped the words of my landlord and a New York City housing inspector.

A few months ago, my fear that I’d soon be dealing with a bedbug problem materialized when I learned that three units in my apartment building were infested with the pests. When I asked my landlord for assurance that the infestation would be dealt with swiftly, he told me not to worry. He had hired an exterminator. But moreover, he said, the building is clean and the tenants are to blame for visiting dirty places like the new lofts nearby where college kids live. When I later relayed my concern to an inspector from New York City’s housing department, he told me that bedbugs were rampant in my area because people purchased used mattresses.

But if what these entomologists found in the multi-unit apartment buildings they visited in Jersey City, New Jersey and Raleigh, North Carolina hold true where I live in Bushwick, Brooklyn, it means that inadequate measures to exterminate bedbugs are more to blame than tenants who pick up the bugs at their friends’ houses and at the used mattress market (if such a thing even exists). The team analyzed regions of DNA from bedbugs they collected in the apartments. To their surprise, they found that bedbugs in different apartments within the same or neighboring buildings arose from a single mother in the recent past. In other words, multiple infestations resulted from one person who brought the bedbugs home, rather than from independent introductions by different tenants.

“Our tentative conclusion is that bedbug introductions into a building are a fairly rare event. It seems more likely that bedbugs spread throughout a building when a tenant drags their infested mattress or other belongings down the stairs,” says Coby Schal, an entomologist at North Carolina State University in Raleigh who presented the study today at the American Society of Tropical Medicine and Hygiene (ASTMH).

If I weren’t living in what may be bedbug ground zero, I might appreciate the extraordinary ability of bedbugs to overcome the problems associated with inbreeding. Normally, the practice comes with unhappy consequences because it gives bad, recessive mutations an opportunity to combine in single individual. Humans realized that inbreeding can be dangerous centuries ago, and made the practice taboo. “Inbreeding avoidance” strategies exist in the animal kingdom as well. Male ants and termites sprout wings to fly far from their mothers and sisters. And male baboons, snub-nosed monkeys, and other primates often disperse from their group around puberty, perhaps to avoid mating with their kin.

Schal says he and his team, including entomologists Edward Vargo, Warren Booth, and Virna Saenz, have submitted the study for publication. He says one caveat of the study is that it included only three sites, which weren’t in highly infested neighborhoods. Perhaps my photos in the slideshow below, taken this summer on strolls around Brooklyn, will entice him to repeat the investigation here:

Related at Scientific American:

Bedbug Revival 2011: What You Need to Know

Flee, Dry and Die: Is a New Weapon in the Bedbug Battle Ready for Action?

Bedbug Treatments Sicken More Than Bites Do

What Are Bedbugs? Are They Dangerous?

Of lice and men: An itchy history