Whether you are asked via email, facebook, by phone or someone with a clipboard questions you on the street, there are some pieces of information that should never be shared. These can be used against you if the questioner were so inclined. They can be used to open bank accounts or break into accounts you already own.
Never share this information but if you do, make something up. If I am asked my mother’s maiden name, I never use her real name. I use a name I heard on some random TV program that I saw when I first came up with the idea. If anyone breaks into any one of my online accounts and uses that piece of information, they won’t be able to use that answer on my bank’s website or in a branch. It will be wrong. The same with birth dates etc.