Childhood trauma is more common, and its effects, both physical and mental, are more diverse and pervasive than current literary theory appreciates

Literary theory already includes trauma studies (1). And many people have heard that holocausts, wars, torture, natural disasters, serious illness, injuries, and child abuse may increase the chances of having anxiety, depression, addiction, and identity problems.

But most people are not aware that childhood trauma, serious enough to have serious consequences, is relatively common:

http://www.cdc.gov/violenceprevention/acestudy/prevalence.html

Moreover, most people do not appreciate the diversity of the consequences:

http://www.cdc.gov/violenceprevention/childmaltreatment/consequences.html

Thus, when anyone is known to have had either childhood trauma or something that is more common in people who have had childhood trauma—depression, bipolar disorder, etc.—you have to consider whether they also have one of the other things that is more common after childhood trauma: multiple personality (whose two most common clues are a puzzling inconsistency and memory gaps, which, to find out about, you have to ask).

1. Gregory Castle. The Literary Theory Handbook. Wiley Blackwell, 2013.