"Why do you ask?" is a good question to keep ready when people ask what is none of their business. Even if they come up with a reason, that is not a reason to a

"Why do you ask?" is a good question to keep ready when people ask what is none of their business. Even if they come up with a reason, that is not a reason to answer. You don't need to say anything at all after that. Let them try to come up with something to fill the silence. A woman whose father killed herself was repeatedly asked how he did it. This question saved her.