We examined this yesterday: she has always said she was a lizard in a past life, and I agree. There are remnant clues: she loves to sit in the sun, whatever the temperature, and soak it in. She also loves lizards of all sorts, always has. We used to own a salamander when I was little. And she spent a recent holiday in the caribbean mainly chasing iguanas around the island.
However: according to Buddhist reincarnation philosophy (apparently), if you are reborn as a creature that slithers so close to the ground it means you did something terrible in a previous life. So she must have been some awful woman before that.
It's obvious isn't it? My mother was previously Marie-Antoinette.
The good news is she must have been an amazingly awesome lizard to be reborn a human woman again. Let's hope she doesn't mess it up (there's still time).