What do Thomas and Teresa reveal about themselves to the Gladers?

From the text:

Thomas shook his head. “As far as I can tell, we’ll probably never know what our names were.”

“What are you saying?” Frypan asked. “That we’re freakin’ orphans raised by scientists?”

“Yes,” Thomas said, hoping his expression didn’t give away just how depressed he felt. “Supposedly we’re really smart and they’re studying every move we make, analyzing us. Seeing who’d give up and who wouldn’t. Seeing who’d survive it all. No wonder we have so many beetle blade spies running around this place. Plus, some of us have had things … altered in our brains.”