A bunch of us have that kind of white skin that in adult years doesn't tan.. it burns in clearly unhealthy ways.
Vitamin D productive begins immediately when the skin is exposed.
With vitamin d it’s about building up reserves while you can, and supplementing with food or vitamins.
My sister and mom tan, I burn. Weird thing though, when I was a kid I spent so much time outdoors. Like, all of the time.
That was before I got hold of a decent computer at like age 12 in 1989, and I started spending so much time indoors.
After 30 years or so of mostly staying indoors, I burn when UV rays hit my skin.
I'm willing to concede that my behavior is at least a part of the issue.