Under what law are you required to fill out that form?
Don't just take their word for it that you're required to do so. Make them show you the law. I don't see any reason for them to know more than name, address, and the number of people living in your household. The rest is none of their business. Just because someone asks a question, it doesn't automatically mean that they deserve an answer.
Or, you may do like so many do on the Internet when registering for a web site address, lie.