Chris’s case had far-reaching ramifications for scientists beyond Nevada. One niggling worry was whether Chris would be the same guy with someone else’s DNA. Dr. “It doesn’t matter,” Dr. Rezvani replied simply.

Andrew Rezvani, a blood and marrow transplant specialist at Stanford University, says yes. “Their brain and personality should remain the same,” he told The Independent. He also stated that if Chris’s donor were female, it would not transform him to the feminine sex.