Yuk yuk yuk. Offspring are all right. Very interesting though. 300 offspring, both parents left-y, but all offspring right-y. It seems curious that left-y is so rare and according to the article additional genetic studies are needed before the left-y cause is determined. Maybe it isn't genetic, but a rare quirk of development.

I was wondering why right-y is so prominent, but if there are physical limitations during mating between left vs right then one would naturally emerge. No mentions of alternate snail species in the article with left-y shells, but apparently left vs right shells are distinguishing features of gastropods (land and sea snails).

https://en.wikipedia.org/wiki/Gastropod_shell

An interesting natural constraint on design. Edit: and by design I mean constraint on emergence / naturally restrained emergence, not some externally imposed design.