Each twin controls her half of their body, operating one arm and one leg.As infants, the initial learning of physical processes that required bodily coordination, such as clapping, crawling, and walking, required the cooperation of both twins.By coordinating their efforts, they are able to walk, run, swim, and ride a bicycle normally—all tasks that they learned at a normal speed.Together, they can type on a computer keyboard at a normal speed and drive a car.Although Brittany - the left twin - can't feel anything on the right side of the body and Abigail - the right twin - can't feel anything on her left, instinctively their limbs move as if co-ordinated by one person, even when typing e-mails on the computer.
In the first episode of the show the twins, who share one body fused at the torso, are shown celebrating their 22nd birthday, graduating from Bethel University in Minnesota and getting ready for job interviews.
While they can eat and write separately and simultaneously, activities such as running and swimming require them to coordinate and alternate their actions symmetrically.
Other activities as diverse as brushing hair and driving a car require each twin to perform separate actions that coordinate with the other's.
What is perhaps most touching about Abigail and Brittany, however, is their ability to get on - despite their different personalities.
They seldom argue, despite Abigail always wanting to be the leader and - according to their mother - liking 'to rule the whole house'.
They attended a private church school and are popular with their friends, who treat them no differently from anyone else.