Unexpected Breeding

So my axies have been back in their tank for about a week after a couple of months fridging. I had Toothless, the male, sectioned off on his own with a divider until yesterday when he managed to knock it down and get in with the girls. Works been crazy the last couple of days so didn't have time to section him off again before I left for work today.
I came home today to find he'd turned the tank into a spermatophore dump, and Astrid proving herself to be far more agile than I thought possible. Fortunately Hiccup is too young to be interested, she's just eating them…

Anyway, so Astrid and Toothless are brother and sister, Hiccup is their cousin. I wasn't intending to breed them, but seeing as it's accidentally happened this time, would it be ethical to keep/sell the eggs or should I just dispose of them?

While inbreeding is generally not the best kind of breeding, as long as it's the first instance of inbreeding the offspring shouldn't have many, if any, deformities or problems. The only real question is whether or not you have the space, time, and money needed to care for the eggs.

Inbreedin is not so much of a problem with axies as it is with mammals, you shouldn't have any worries other than how many eggs to keep.

I kept about 50 eggs in total, kept some in my outhouse to slow them down so I could stagger the hatching, I have 30 healthy babies, 20 more to come, and I've only had 4 casualties. You may get a few more natural deaths with a sibling pairing, but thats just nature's way of ensuring survival of the fittest.