In 2017, in the United States, there were nearly 35,000 transplants of lungs, hearts, kidneys, intestines, and other organs, according to the United Network for Organ Sharing, and by no means were the transplants done between identical twins, let alone siblings. The best possible matches are made on a number of bases, including blood type and the similarity of antigens. Even after a successful transplant, though, the recipient can need a lifelong regimen of immunosuppression.
