If user clicks on pedigree bitmap by accident, there is no way out unless user either picks a template or import file. The Close button should enable user to go back to the previous page.
I think in most cases a cancel button will look confusing if you actually want to create a pedigree. Maybe the dialog should keep the [x] in the corner which, when pressed, would close the pedigree (this [x] exists if you try to import into an existing pedigree, but hidden if the dialog is displayed for an empty pedigree which is being initialized)
Agree. An [x] would be better than Cancel button.
I would show [x] for a brand new pedigree (not yet initialized) as well and if pressed user should be redirected to the page where pedigree editor was open (patient or family form).