There is skin cancer in my family. My grandfather has had it, and occasionally a doctor will try to tell me that I am genetically predisposed to it because of this. While I try to practice good sun habits, I am dubious about the "genetic predisposition" argument. You see, my grandfather spent several years in the early 40's hanging out in the sun in the Phillipines while monitoring Japanese aircraft activity. He thinks that's more responsible for his skin cancer than genes. I do too.
Regardless, you might say, it's a good idea to wear sunscreen right? Of course. Except it may not help.
As it turns out, sunscreen formulas that prevent sunburn may not be equally good at preventing cancer. And you may not be putting enough on. And they may have chemicals in them that actually increase your cancer risk rather than decrease it. Huh.
I've talked before about making sure you connect all the dots, not just proving disjointed ideas. We know that sunscreen prevents sunburn, and people who get sunburns are more likely to get skin cancer. The troubling part is that there is no proof that people who wear sunscreen get less skin cancer. It's tempting to jump from A to C, but you have to remember things can go wonky when you don't remember the stop at B.
Regardless of the data, sunburns are painful, and I'm still very Irish, so I would recommend sunscreen in general...but lets not oversell the good it might be doing.