Chicks with hole in abdomen

[ijustsawachickeneatafrog]

The other day, the first lot of eggs which were under one of my broody hens began to hatch. I had bought 6 purebred pekin eggs to incubate, and 3 died in the early stages of incubation whilst the other 3 developed.
The first one which hatched appeared completely fine, although when I went to check in it later it had died (could be due to the hen, there's no way to tell).
The second one which hatched came out with a fairly large hole in its abdomen, a bit below its vent. I had thought it had been stuck to the side of the egg and it had happened during hatching, although there wasn't any bleeding and the skin wasn't torn. I patched it up and am hoping it heals alright.
Anyway, the third and final one never hatched. I opened it a bit earlier today and found that it was dead but fully developed, except it also had a large hole beneath its vent. It's organs had come out, which I'm guessing is what killed it.
Is this a normal thing? I've never had it happen before, and I suspect the parent birds might have been related.
The chick that's still alive is also really weird, like it's completely silent except for some random happy/snuggle noises which are very out of place. It also seem to have a bit of trouble seeing as well.
I don't have any photos, unfortunately, though I wish I did

 

[Chickenchickwithchickens]

The parents of the chicks may have had genetic problems that were passed down to the chicks. That's so sad. I hope your one chick makes it.

 

[ackie]

Is the hole where the yolk would be absorbed?

 

[ijustsawachickeneatafrog]

I'm not sure. I did some research and I think it might have been a hernia. I had an unrelated chick hatch yesterday with the same thing.
The first chick is doing great now, though.