The answer is halfway between....some people are bitten more than others, and some are more sensitive to the allergens than others. Lots of work has been done on bite attractants. The biggest one is co2, which you breathe out. mossies follow your breathe to you. After that, at close range body temperature seems to play a role. Any deviations from the norm make you more unlikely to be bitten. Then its pheromones, which is where blood group etc. canplay a part. I use pheromone in a very broad , and semi innaccurate sense here...meaning any trace chemical given off in sweat or breathe. For exxample tsetse flies are attracted to octanoic acid, a component of vegetable digestion, often found in cow breath. Some things repel them. Garlic seems to repel mossies to some extent. so does testosterone, so bodybuilders rarely get bitten....There are lots of factors. if you are one of the bitten fol;k, just think of the service you are doing attracting the things away from the rest of us.