I agree with Sunny...I'm sure most people know but just don't want to. I have two brothers, a son, and a daughter. All are healthy and none of them have even offered a kidney to me.
I have a bunch of healthy relatives that have not offered to donate. I have others that have mentioned they want to donate, but for whatever reason will not go through the needed testing. I have my father that went through all the testing (he matched 3 out of 6 antigens), THEN decided not to donate. I think fear keeps most people from donating or causes them to put it off for another day. Another thing... I feel like I can't ask anyone flat out for their kidney. Who am I to demand the internal organs of another person? I feel like they should feel so strongly about donating that they come to me.