When I answer the phones during my show, I’m never 100% positive what will happen. I have a producer who screens the callers to make sure they want to comment on the topic I’m discussing, but the only info I want her to give me is the caller’s name and a couple of other basic pieces of information. Apart from that, we fly without a net, and it almost always works smoothly.

There have been occasions, however, when the content of the call is so compelling that it has knocked me back in my seat. These are always the most personal stories, and often the most heartbreaking.

I had one of those today.

It started with a moral dilemma based on a story I’d seen in the New York Times about a man in Toronto who needs a kidney transplant. If he waits on the regular list, it could take a long time. But if a family member is a healthy match and willing donor, they can donate directly to him. So, his adult children get tested and, in the process, the doctors discover that one of his daughters is a perfect match to be a donor — but a genetics test shows that she’s not biologically his daughter. The dilemma: should they reveal this family secret? If so, do they tell her? Do they tell him? Do they do the transplant first? Think about the privacy laws, the impact on the family, etc.

I come down on the side of telling her, because if it’s me, I’d want to know. Besides, even if he’s not genetically linked to her, he’s still her father. Anyone can make a baby, but it takes a helluva lot more to be a daddy.

Listeners called with every opinion you can imagine. Tell them, don’t tell them, tell her but not him, tell him but not her, tell the mother and let her deal with it.

In the midst of this discussion, there was a call from a woman who said she could relate to the story because she had gone through something very similar. Her daughter had became extremely ill at age 24 and needed a bone marrow transplant. What the mother knew, but the daughter didn’t, was that the woman’s husband had not fathered this child. The baby had been conceived during an affair with another man, who she never told about this offspring because he was married and had five kids of his own. They hadn’t spoken or had any contact in all those years. The mother had never uttered a word of this secret to her daughter, either. What to do?

For this mother, there was only one possibility when her daughter got sick. She went to the biological father (in person), told him the truth, and asked him to be tested as a possible bone marrow donor. She also asked that his children be tested. Remarkably, they all did. In the face of this amazing revelation out of the past, everyone stepped up to the plate for the 24-year-old, putting aside their own life puzzles to try to solve hers.

Fortunately, it turned out that one of the kids was a match, and doctors performed the transplant. Unfortunately, it wasn’t enough to save the daughter.

What would you have done?