A huge genetic mystery cleared up for a family with a story grabbing attention across the globe.
Geneticist Barry Starr, who works at Stanford and runs the Ask A Geneticist website for San Jose's Tech Museum, used technology to solve the international mystery -- a father was told his son had "none" of his DNA.
After giving the parents a genetic test from Silicon Valley's 23andMe, Starr found the child's DNA was that of the father's twin brother, who was never actually born.
"It's really no different than two brothers at a very early stage before the immune system is set up," Starr said. "The two fuse together and become a single person."
The man is in genetic terms a chimera, like the hybrid monster of Greek mythology. But in this case a person born with two sets of DNA, one of which his one-time twin's DNA was passed on to his son.