Mosquitoes are attracted to a chemical that people produce and some people produce more of that chemical than other people so it could be a reason that mosquitoes are attracted to you more than other people if you're producing more of that chemical than other people.
Also mosquitoes are attracted more to certain blood types than others and it could be that you're the blood type that mosquitoes are most attracted too.
Blood type O tends to attract mosquitoes more than the blood types A or B and Mosquitoes are also attracted to the CO2 "Carbon Dioxide" that we exhale when we breath and that Carbon Dioxide is what first attracts the mosquitoes to a person.
When sitting outside you can keep mosquitoes away from you by placing an electric fan outside and let the fan blow on you.
The wind from the fan will keep the mosquitoes away.