The peculiarities of Jake and Jan (their families asked that their real names not be used) were apparent from an early age.

As a toddler, Jan sometimes spoke using her own language. Instead of "cookie," she would say "cookah" and refused to call a sandwich anything but a "phonic." Odder still, she didn’t begin speaking until she was three years old.

For Jake’s part, he had trouble grasping the concept that he was not in charge. "He has to be told," Jake’s mother says. "He doesn’t think he needs permission." Spence noticed a similar idiosyncrasy in her granddaughter. "You have to coax her to do her homework," she says.