In feminist theory, there is a distinction between sex, something that is biologically given, and gender, which is socially constructed or performed. Sex is a matter of DNA, and determines ones ability, for example, to become pregnant and bear children. Gender determines ones role in parenting. Whether one is the primary caretaker of a child does not depend on whether one is biologically male or female.
Much of feminist literary criticism looks at how writers construct gender, and the relationship between gender performance and biological sex in literary works. Another interest of feminist critics is how specific literary traditions have been complicit in the cultural construction of gender identity (e.g. the romance, the western, etc.)