Bad Biology

Exactly what it says on the box: bad biology. This can range from completely nonsensical illnesses/cures (athelas cures, like, everything! Colds! Flu! Cancer! Syphilis!), to illogical genetics (I'm descended from Sauron! I have, like, red eyes and black hair!), through to anatomical ignorance (e.g. Land Before Time: Littlefoot x Cera - dinosaurs with mammalian sex organs).

Fics with poor biology are encountered by most departments, but fics where biological charges are in the majority usually end up in the Department of Bad Slash or Division of Bad Het, although it is arguable that the Department of Mary Sues sees the most illogical genetics, which is a standard feature of Mary Sues.

Bad biology often angers agents, who react in various ways - from violently killing the perpetrating OC, to throwing themselves in the Fountain of Bleepka, to giving an angry lecture, involving diagrams, about anatomy.

It should be noted that what constitutes "bad" biology can vary depending on canon, as more fantastical or comedic worlds are likely to feature biology which doesn't work in the Real World. For example, in Gorillaz canon, head injuries make one's hair turn blue, and in Land Before Time, dinosaurs have eyelashes. In cases like the aforementioned, it's generally best to assume that things work the way they do in the Real World unless canon specifies otherwise; one canonical biological inaccuracy does not mean ficcers can throw all the laws of nature out the window.

Badficcers who need lectures about biology include the author of That Series, the author of C*l*br**n, the author of For Your Eyes Only, and AJ Matthews, who is a frequent user of the Mpreg plot-device and often makes male characters have sex with no lubricant, which is considered a bad biology charge.

Bad biology is a large contributor to squick.