Depending on the country, and they type of clearance? I got one years ago, but civil (government). I found it odd I was asked about my grandparents' occupatio

Depending on the country, and they type of clearance? I got one years ago, but civil (government). I found it odd I was asked about my grandparents' occupations. No harm came. Large companies, particularly those in finance, also ask for clearance which they also call security clearance. That's mainly ensuring a clean track record. One big area that I've seen people mess up is 'Directorships'. Having once registered a company, and keeping that company running, is a directorship, even if the company is idle. It takes a lot of unwinding with HR and audit when these things that are often only sometimes checked, or an international check is not run. Do declare directorships; as long as there is no conflict of interest there's noting to worry about, and if there is a conflict of interest, get it in the open because you could be accused of criminal liability.