If Gender
is a boolean then what would you expect? If it isn't a boolean then that would be odd.
EditorFor
just looks at the top of the property and selects a default control (textbox in most cases). In your case if you want a dropdown then use DropDownList instead. If Gender
is an enum then you tell it what enum to render (which sets the label and value) along with the value to bind against. Under the hood the select item that has a value that matches the value of the property is marked as selected when rendering and set when posting.