I just received a request for a bunch of personal details as a task with a deadline in one of our HR workflow systems. I don't have the choice to opt out of it and I don't think it is any of my employers business what my ancestry or sexual orientation is. Is it legal in the US for an employer to demand this information? What is the worst that can happen if I just don't respond since I don't have an option to decline?
Edited to bold the part of the post I think most replies are missing.