On average one person in 10,000 has the congenital condition called situs inversus, a congenital state in which the bigger organs in the thorax are on the opposite side of the body from usual.
This rare condition usually causes no problems and goes unnoticed. Donny Osmond and Enrique Iglesias have it and so too did Rose Marie Bentley, from Molalla, Oregon, although she did not know it. When she died in she donated her body to science.
At 99 she is thought to be the oldest person with the condition, which can be accompanied by serious heart defects.