Apparantly lying is a genetic issue for me...

I got a call from my grandmother today who I haven't spoken to in 20 years. We've exchanged letters, but thats about all. I asked her for some family history and here's what she told me:

Her grandmother (my great great) was some sort of Native American. Her husband came here from Germany and married her and changed her name to Lucretia. From that day on, she was not allowed to talk about the time before they got married. Now no one knows anything about her. Even my grandmother's brother, who was close to her, could not get any info out of her. We have no idea what tribe she was from or even what her name was before they married. She took it with her. This is making me insane.