Why Do Mosquitoes Target Certain People?

No one knows:

I wish there were a simple answer, but scientists have only isolated a few potential causes. It is likely that the full story remains to be elucidated – and may be related to small genetic variations in human odor. However, we do know that mosquitoes are attracted to carbon dioxide (that we expel as we breathe), and warmer skin temperatures. So I guess if you’re a heavy-breathing, hot-blooded person then you might need an extra layer of DEET?