Mistakes happen, people miss-key, database entries get put in the wrong field, ... I imagine that if the entry didn't match the format for the field then you're open to the bank clerk being socially engineered more easily.

It's like if a password field said 'no punctuation, maximum 8 characters' and your password was much longer with lots of characters; particularly if it looks random it could appear to be a corruption.

I imagine the range of given names gives most password entropy, so "family pet" might be the best question to choose, especially if you never had a family pet.