Thanks to Sally for sending in the below letter to the Ethicist -- and his answer -- from the New York Times. She says, "The idea that people who have had emotional problems in their past are more likely to be violent or harm children is absurd and common."

My nanny recently told me that she takes antipsychotic medication for a bipolar disorder. I’ve been happy with her for the past two years. She seldom spends long hours alone with my children because I am a stay-at-home mother, and she would never knowingly harm them, but people with psychosis can’t always control themselves. You don’t fire someone for a disability, and I feel a particular sense of obligation because she is a young undocumented Haitian, but should I dismiss her to protect my children? — K.V., Brooklyn

You should not fire your nanny. Your anxiety stems more from lurid notions of mental illness — “Psycho” and “The Snake Pit” are not documentaries — than any real risk to your children. Your nanny has never endangered them; you’ve long admired her work.

You are restrained not only by ethics but also by the spirit of the Americans with Disabilities Act. An attorney I consulted says that if you ran a larger business, “to fire her would be illegal.” Were she to stop taking her medication or otherwise display dangerous behavior, a business could dismiss her. Fortunately, as a stay-at-home mother, you can see if her condition deteriorates before anyone is imperiled.

Her immigration status already restricts her other employment prospects, and her limited options, as you imply, impose an additional ethical burden on you. If she can do the job, she should be allowed to keep it.

He handled it well, but this is a perfect example of stigma when you least expect it. I'm sure after two years the nanny felt she could confide in the woman she spent every day with, and whose children she loved and cared for. It's the kind of story that makes me reluctant to tell people what I do.