[jawns]

I don't think you need to divulge any sensitive details, but unless this is a "one in a million" occurrence, it's possible that others might be faced with a similar situation in the future, so it might be useful to share at least some broad details. Was HR concerned that it would lead to legal problems, e.g. an ADA violation or a claim of discrimination against a protected category? Or was it more like a nepotism issue? As a manager, I would likely handle those in different ways.