Got a lesser version of the luck Bigtex has. By myself, I can get bitten, but standing next to my wife I'm nearly immune, while she needs a transfusion.
Mosquitos supposedly find their meals by sensing the Carbon Dioxide when humans and deer and their other food groups exhale. Same method with Tics, even though they get to their meals in different ways, even though one is an insect, the other an arachnid. None of this explains why some people attract them more than others, however. Shitty thing about Tics is you can carefully avoid brushing up against any vegetation, but some Tics can drop down from overhanging branches ... their scaled down version of "Death From Above."