On further reflection it sounds like they all have a digestive impaction and what they have eaten is now going rotten in the crop and gassing up. I very much doubt this is genetic and so it must be a digestive reaction to the feed or water additives.
All you can do is just give them plain water and hope their system clears. No point in giving them feed if they can't digest it. I assume your tap water is safe to drink? I ask because ours certainly isn't and if we reared chicks here they would be on bottled water without added minerals, as we are.