In the year 2000 post rebirth, the great scientist Yman One spoke to a young audience on the tenth anniversery of the founding of the first Mars colony. The title of his talk was, "Double DNA and the X9 marker. Myth or science?"

After his speech, which drew a standing ovation, Yman was approached by a tall young woman, marred by a slightly hunched back. "Excuse me," she said. "But I have the X9 marker in my DNA. I don't understand how you can claim it does not exist."

Yman looked at her oddly, as if he hadn't heard her. "Every single human on earth was tested when we started universal health care last year. And not a single person showed the X9 marker. Clearly you are mistaken."

The girl scrunched her face. She closed her eyes and seemed to concentrate before answering.

Yman was about to turn and leave when she spoke.

She said, "woof."

Yman's eyes went wide, startled. "Your parents, of course. They live here on Mars with you. I hadn't thought of that."

Then Yman felt unaccountably sad and said, "I'm sorry."

The girl asked herself, "How did I do that?" Then she turned, her head filled with new questions, and ran off to find her parents.