Kitten born with a birth defect

My friend has a young mother cat who got pregnant her first heat cycle (she got out by accident). She gave birth to 3 kittens, 2 normal ones and 1 who appears to have the stomach and/or intestines not quite in the right place - they appear as a lump around the left hind leg. Is it an intestinal malrotation? I've been trying to find some information online about it, but haven't had any luck. I would like to adopt him, but would it be better to have him euthanized? He eats fine and wriggles like a normal kitten and the mother takes care of him properly.

You really should have him looked at by a feline specialist vet.  He may well have a hernia which could easily be repaired and he could live a long healthy life.  However if it is a hernia and the intestines remain outside the abdominal wall, they will eventually cause problems.  You did not mention how old the kittens are now, but this requires a vet's opinion, and preferably a cat specialist who would be the most knowledgeable on the subject.  Let us know what the vet says!

He's only a couple of days old (and yes adorable). Not sure where the closest feline specialist is, but we have a good vet locally. I will have to see if I can take him (well, his mama and siblings too of course). Surgery would probably be a few hundred (minimum) I'd guess.

Have you seen the vet yet to inquire about possible surgery to repair the problem?