I imagine here in the U.S. when they first started breeding pyxies the only pyxies that would breed were bred. So they weren't selected for size as much as willingness to breed. I'm sure many of you know breeding pyxies is a very very difficult task which is why the biggest pyxie supplier in the U.S. uses hormone injections to breed them regularly. Personally, I feel that the hormones might be the cause for a lack of size with these frogs.