“I’m sorry we aren’t covering this cancer claim with our health insurance product because you are genetically predisposed to it”

You almost got this right…

It’s more like, you’re mother submitted DNA and she’s predisposed, so YOU get denied. And that will go back a few generations.

And when it’s something like a 2nd cousin submits DNA and is predisposed, they won’t deny you specifically, but they’ll raise your rates without letting you know why.