These last 10 to 15 years, I’ve been pretty vigilant. We live by the sea and keep a big selection of sunscreens, with SPF ratings of 30 to 45, near the front door, so it’s the last thing everyone sees before heading out. I wear a hat in the sun, cover up on the beach when not in the water, apply sunscreen year-round.

And I go to my dermatologist for regular checkups.

Most visits, she pulls out something that looks like a welder’s torch but instead of fixing the kitchen sink, she blasts me with liquid nitrogen chilled to 320 degrees below zero, which freezes and kills patches of dry, potentially cancerous cells. It takes a few days for the scabs to fall off, and until then if people ask I just say it’s a mild case of plague. The last few years, she has also sliced off pieces of me to be biopsied. Recently, she called to say two had come back cancerous — basal and squamous cells — and I needed to schedule a follow-up with her staff to have them removed. “Tell them you need a three-slot surgery,” she said.

Older white men like me are the worst when it comes to skin cancer rates. While the death rate from melanoma — the most severe skin cancer — has been declining for 20 years for people under 50, men over 50 have the highest increase in death rate, 3.2 percent a year since 2002. The highest annual increase in incidence of melanoma is among white men over 65, 8.8 percent a year since 2003. And while there’s also rapid growth among young white women ages 15 to 34 (40 percent of 18-year-old women have used a tanning bed in the last year, compared to 8 percent of men, according to the American Academy of Dermatology), nearly twice as many men as women die of skin cancer each year.

So here’s what I can’t figure: How could I have been so stupid? How was I so oblivious for 40 years, and could I blame my mother for any of this? Dr. Darrell S. Rigel, 59, a past president of the American Academy of Dermatology, and editor of “Cancer of the Skin,” a leading textbook in the field, advises against blaming mothers. “My own mother would spend hours tanning in the backyard, and developed a melanoma,” he said. “The public awareness on this is relatively new, 20 to 25 years.”

The progression from serious sun exposure to skin cancer can take decades to unspool in our DNA. “What we’re seeing now, in increased rates of melanoma, is what people did in the ’80s,” Dr. Rigel said. “Baby boomers out baking in the ’80s.”