Recently on a BBC morning program that I watched while off due to being ill for three weeks, there was a family with a bit of a kidney disease problem.
All three children had a heredity kidney problem. Their middle child, the younger daughter, was the first to have a serious problem and a transplant was required. Up steps the Mum, a perfect match, and she donates one of her kidneys. Some time later the youngest, their only son, also had his kidney problems increase until he too needed a transplant. Up steps Dad, a perfect match for the son. And another transplant takes place. During their interview, eyes gradually drifted towards the eldest daughter. So the interviewer asked the obvious question - what how are your kidneys? Luckily they were not as bad as either of her siblings. However she did look a trifle worried as she couldn't get a kidney from either parent now, and would have to take her chances on the open market, so to speak. Let's hope that she doesn't reach the transplant stage!