Of course, he sees the resemblance immediately. Nothing in the Force indicates a lie, either, though the Force occasionally has a creative interpretation of truth. So, logic may be currently missing from this conversation, but that's hardly going to keep a grin from stretching over Luke's face.

"Well, then," he says in his best 'talking to children' voice (excuse him if he's lacking in practice), "nice to meet you, Jaina. Would you mind telling me how you got here?"