You and all of your family member are bound by a curse, the details of which are up to you and the GM to determine, however whatever the curse you're bound by it. Only powerful magic or the intervention of a deity could lift the curse.
Regardless of the family curse, the GM is able to once per session call upon it to force you to reroll a single check and take the worse result. If the GM uses this during a session, you can choose to reroll a single check during the session and take the better result.