Research shows that under similar control settings, mosquitoes tend to bite specific people more than others. This was initially puzzling, but advances in science have shown why this is so. There are some biological reasons why a mosquito might prefer biting one person rather than the other, and one of these is the blood type.
People with blood type O are twice as likely to be bitten by mosquitoes compared to other blood types such as A and B. The specific reason for this is still unclear, though repeated tests will still show that this is actually a fact.
In addition to that, some people produce more carbon dioxide more than others. This is usually down to many factors including the state of their respiratory system as well as their body mass. Whatever the reason, the mosquitoes are usually attracted to human beings by detecting this carbon dioxide, sometimes from many feet away.
If you happen to produce more carbon dioxide than other people when breathing regularly, you are then likely to be a more suitable candidate for the mosquito to bite. Another example of this is women who are pregnant. These tend to produce 21% more carbon dioxide than non-pregnant women, and for this reason attract more mosquitoes.
Personal scents also play a role in attracting mosquitoes. The oils produced by the skins of different people have different scents, and some of them have been shown to attract mosquitoes. The type of scent that one produces is determined by genetics more than any other factor.