Thanks for the comments guys/gals. If you've downloaded/installed the new version of Mysidia Adoptables script before Jan 2nd, make sure you get the new /classes/class_breeding.php file from this link:
http://mysidiaadoptables.com/forum/s...ead.php?t=5704
The new download links already have the issue reported by Abronsyth fixed, so it will not affect any new users/installations.