It happens occasionally in the wild as well. The recent prevailing theory ( not tested) is that it is probably caused by too high temperatures during fertilization and early gestation.
Most ray keepers keep their rays temp much higher than wild conditions and without any natural temp oscillation.
High temps are a very well known mechanism in genetics for birth defects across all species.
There was a decent discussion here
http://www.roggenforum.lode.biz/forum/viewtopic.php?f=26&t=3210
Most ray keepers keep their rays temp much higher than wild conditions and without any natural temp oscillation.
High temps are a very well known mechanism in genetics for birth defects across all species.
There was a decent discussion here
http://www.roggenforum.lode.biz/forum/viewtopic.php?f=26&t=3210