Where was Tara from?

They kept alluding to Tara's past... about how she didn't want to go back to where she came from or what she was. She says that after what she experienced she thought she lost her emotions and ability to love.

But they never tell you where she came from or what happened to her.

I kept waiting for them to say that she'd been a monkey or something in the jungle that the scientist had evolved into a woman.

My second guess is that when she was a girl she was caught on the outskirts of Hiroshima or Nagasaki in 1945, had witnessed horrible things and had to do awful things to survive (and maybe the scientist had treated her for radiation poisoning or some such).