wrote on Feb 3^rd, 2017 at 12:00pm:

Had an interview with an oil company.  They asked if I had a relative working for a government agency.  I replied no.  After the thank you note was sent I realized that I had forgotten that my brother worked for the government.  I went back and corrected the answer on the online application after I was also asked in the interview and responded as No.  Should I call the hiring manager and explain the mistake?  The interview went well and the follow up response is said to be next week.  Leave it alone or call?

At least, in the private sector (except for private security and pharmaceutical firms) you won't have to worry about being polygraphed as part of your application.
Ironically, federal law prohibits use of the polygraph in the private sector with the two exceptions noted above.  Yet, the federal government remains the largest (mis)user of the polygraph for employment screening. :o