While it's important to be open and honest with a potential employer you should realize that there are some questions that an employer cannot ask and that you are not legally required to answer.

What They Can’t Ask You

1. Where you were born? (They can ask if you are authorized to work in the U.S.)
2. Are you married?
3. Do you have children?
4. Do you plan on becoming pregnant?
5. What language do you speak at home? (If the job involves speaking another language they can ask if you speak that language.)
6. How old are you?
7. Do you have a disability or illness? (They can ask if you are able to do a specific physical activity if it is part of the job.)
8. Do you observe any religious holidays? (They can ask if you are available to work weekends and holidays.)
9. Are you in the National Guard or Army Reserve?
10. Do you smoke or use alcohol? (They can ask that you take a drug test.)

See more questions that cannot be asked during an interview. Also, see specific questions an employer can and can't ask you.  

To file a complaint about illegal questioning during an interview, contact the Equal Opportunity Employment Commission.