He feels her shift. Spy training tells him to read her body language and simple logic tells him that if Jyn is lying in his bed, arms around him, then a simple shift of her head is far less indicative than it might usually be. When he dials those instincts out, he hears her properly and frowns a little at that. Where a person is born isn't the end all be all of one's identity but in a galaxy as easily traversed as theirs, it still means something.

"Is Coruscant the first place you remember?" he asks. Is it the first place she thought of as home? He knows that at some point, they came to Lah'mu, where the Empire sent Krennic to extract Galen. The details on her file are fuzzier after that. Time spent with Saw Gerrera obviously, various aliases, and then Wobani prison camp. It's an unfair advantage for two people who live by secrecy and survival.