Getting some colour in my pasty-white legs

Factual Questions
1

Man, I’m full of questions today.

Why don’t my legs tan (or burn)?

I am pasty white. For me, eggshell or off-white would accurately describe a tan. Parts of me burn like a sumbitch. I can’t take off my shirt in the sun w/o SPF30 and even then I can’t keep it off. My nape is also particualrly at risk. My face burns as well, but it takes longer than my torso. My arms burn at a slightly slower rate than my face.

And then there’s my legs. These things look like a couple of pillars at the Acropolis. White as the driven snow. But they won’t tan and they won’t burn. Well, they will burn, but really only a little part right above my kneecaps.

The other day, I was out in the sun unprotected for a couple of hours (I should really carry sunblock around in a little holster so that I don’t find myself out without it). I came home with a very red neck, quite red face, slightly red arms, and pasty white legs. Even self-tanning lotion stuff doesn’t work on my legs as effectively as it does on my arms or face. Why the differences between my various body parts?

2

This is just a guess, but your neck is probably almost always exposed to the sun, while your arms a little less so, since they may be covered by your body at times, and your legs may be in a shadow often times as well, protecting them from sunlight.