My brother once came up for a bloodtest which turned out to be a 100% match. But the more tests were done the more scared he became, so he refused in the end without further explanation apart from: he didn't want to become ill like me. Duh
The other brother actually told him at xmas "I hear you can buy a new kidney if you have enough money." I was flabberghasted.
I couldn't bear to let this by without comment. While I don't believe anyone is obligated to donate a kidney for family or anybody else, there is no excuse for ignorance like that. I know that if I donate a kidney, then aside from immediate risks of surgery, I will be left with sufficient kidney function and go back to a fairly unremarkable life. It is a lot easier to live with one healthy kidney of your own than to maintain a transplant.
He would be like [the recipient] in a sense of "having one working kidney". He would not be like [the recipient] in the aspect of having to deal with renal disease forever.