Why Mosquitoes Bite Some People More Than Others

Mosquitoes don’t bite everyone equally: some people are consistently more attractive, and genetics appears to play a meaningful role. In a lab setup at New Mexico State University, entomologist Immo Hansen used a Y-tube airflow test to measure how many mosquitoes flew toward a human arm placed in one chamber versus a control chamber. Derek—who reported being the one in his group who gets bitten—turned out to be a strong attractant: nearly all mosquitoes moved toward his side, while the other side received little to none. The result was striking enough to mirror his real-world experience, and it set up a deeper question—whether DNA differences help explain why.

Earlier research used the same Y-tube approach on twins to separate genetics from shared environment. Scientists tested 18 pairs of identical female twins and 19 pairs of fraternal female twins, then quantified mosquito attraction by the fraction of mosquitoes that correctly flew to the arm where each twin stood. Attraction scores between twins were correlated for both types, but the correlation was stronger among identical twins. That pattern points to inherited factors influencing body cues mosquitoes use to locate hosts, rather than diet or environment alone.

To probe that idea directly, Derek and his wife Raquel ran a controlled comparison in the lab, swapping who was placed in the Y-tube. Their anecdotal pattern—Derek getting bitten while Raquel did not—reappeared under lab conditions, with more mosquitoes ending up on Derek’s side. The experiment wasn’t presented as a rigorous clinical study, but it provided a practical match to the twin findings: individual differences can be large even within a household.

Next came the genetic check. Using 23andMe data, they focused on seven DNA locations previously linked to mosquito attractiveness in a 2017 genome-wide association study. The analysis suggested they were identical at four of the seven sites, leaving three where they differed. At the first two differing sites, Derek carried variants associated with decreased attractiveness (more “protection”) relative to Raquel. But at the final site, Derek had two copies of a variant associated with increased attractiveness, while Raquel had none—an alignment that fit the lab outcome.

The transcript also links these genetic differences to the chemistry mosquitoes follow. Carbon dioxide is a major cue, and higher metabolism, exercise, larger body size, and pregnancy can increase CO₂ output. Mosquitoes also track other volatiles such as lactic acid, acetone, and ammonia, while certain compounds—octanal, nonanal, decanal, and 6-methyl-5-hepten-2-one—can repel or disrupt mosquito host-finding. Skin microbes (the microbiome) likely influence these odor signals too.

Finally, the stakes are public health. Mosquitoes are described as the most consequential animal for human disease transmission, with malaria highlighted as a parasite-driven system that can alter host chemistry to make people more attractive to mosquitoes—helping the parasite spread. The episode frames mosquito attractiveness as a heritable trait on par with characteristics like height or IQ, making it a potentially important target for future prevention and risk reduction.