Science has a proof that mosquitoes are more attracted to some people than others. And the reason for this probably lies in one's genetics. It is a well known fact that mosquitoes need our blood proteins to make their eggs, hence only female mosquitoes are involved in the role of biting human beings. The eggs first hatch into wriggly larvae which further develop into pupae before becoming flying adult mosquitoes. They further suck out vertebrae blood to make more eggs . The whole lifecycle takes just two weeks. 

In order to get clear picture, Researchers recruited eighteen pairs of identical female twins and nineteen pairs of non identical or fraternal female twins. Then they performed the Y-tube test to evaluate the mosquitoes attractiveness of each individual measured by the fraction of mosquitoes who correctly flew to the arm of the tube where the twins were standing.  By doing this what the scientist found is that the mosquitoes attractiveness of twins is positively correlated that is the more attracted you are to the mosquitoes, the more likely your twin is too but that could also be due to other probable factors like common diet, common environmental surrounding. But comparing identical twins to fraternal revealed the correlation was higher for identical twins. This strongly suggests genetic influence how attracted you are to mosquitoes, Since the identical twins share more of the same genes than the fraternal twins. 

What the scientist did was a genome wide association study, that is they looked at all the DNA of all those participants and tried to see if there were commonalities amongst the people who said they were different to the people who said they weren't attracted to mosquitoes and they identified seven particular locations on the DNA . There are seven single letter changes which seemed to be associated with different levels of attractiveness to mosquitoes. As of today it is not so clear how these genetic changes might make us more or less attractive to mosquitoes but it's likely that it also has something to do with the odor or the volatile chemicals that our bodies give off and due to microbiome, the bacteria on our skin. One of the main signals that mosquitoes like to follow to is carbon dioxide that means if you have a higher metabolism or if you have just been exercising you and more likely to attract mosquitoes. But mosquitoes are also attracted to some other volatiles that we give off things like lactic acid, acetone and ammonia.