Mewgenics includes the ability to obtain cats with real-life congenital abnormalities, playing off of the stigmatization of them in the actual eugenics movement. According to co-creator Edmund McMillen, he and co-director Tyler Glaiel received many pitches and ideas during development from fans living with these conditions on how to represent them in a positive light in the game. McMillen (who himself has dyslexia) wanted to include them to show that they can carry in-game advantages in spite of their concurrent drawbacks (i.e. cats born with dwarfism have exceptionally high luck), tying these into the game's greater theme of "making it work [with] what you're given". In line with the fan participation, the in-game portrait for autism is modeled off the TBH Creature (also known as the Autism Creature), an MS Paint drawing by Twitter user @acmeiku that went viral on Tumblr and was jokingly referred to by some as an unofficial mascot or spokesperson for the disorder.