This is a good question and a confusion I see often in my practice. Keeping interview questions “business related” does not mean that the questions must overtly deal with business related subjects. What needs to be “business related” is your purpose for asking the question.
Let’s take the question about books the applicant likes to read. If, for example, the job requires a lot of reading and absorbing information from books, articles, web pages etc., you would want to know if the person likes reading and can absorb information that way. Some people don’t like reading for one reason or another and a job with a heavy reading component would not be a good match. That would be a business reason for wanting to know if the person likes reading.
Of course, if the job has a heavy reading component, you could simply say that the job requires a lot of reading and ask if that would be a problem for the applicant? Chances are, a candidate hungry for a job is going to say “no, it won’t be any problem”. And you will not have learned anything about the applicant.
If, on the other hand, you asked the candidate “What book are you currently reading?” you can get a range of insight into your candidate—including whether he or she likes reading.
There may be many business reasons to ask this question. For example, the job being filled may require the successful candidate to be curious. Maybe they would have a research and development role, or quality control, or loss prevention, or will handle internal investigations. Such positions require people to be inquisitive and to keep “tugging on strings of information” until they resolve a problem. Why is that? What about that? What if we try this? Determining whether the candidate had a love of learning and reading and gathering knowledge could help identify whether the candidate has that required job qualification.
Asking about activities outside of work, such as reading or spare time activities, even though not “business related” on its face, is a permissible interview question and is not considered to be discriminatory because it not designed to obtain information about a protected category (race, age, religion, national origin etc.). Of course, the same question needs to be asked of every applicant for the same job that gets to the point in the interview process when that question would be asked, so that all applicants for that job are treated the same.
It is possible that the applicant could respond with information that gives you insight into their religion (e.g., they prefer to read the Bible, or other religious literature); or their national origin (e.g., they mention that they are reading about the history of the Philippines because they want to understand where their family came from). Obviously, such information cannot be the basis for a hiring decision, one way or the other. But, then again, you might gain insight into something your applicant is passionate about – murder mysteries, or science fiction for example. Questions that are designed to help you understand whether the applicant is a good fit with your company culture are also perfectly permissible.
Identify the business skills and qualifications you seek, along with the cultural values you want your applicants to have and design your interview questions to provide information regarding those requirements. By taking this step to prepare in advance, you provide your company with a layer of legal protection in the hiring arena.