Names are such a culturally different thing, and it's interesting to see how software grows around the culture it's written in and how walking into it from a different culture can feel.

Anglo-centric view here (given that's where I'm from), but just living in Puerto Rico for a while was interesting. The culture there predominately has two surnames, one from each parent. When I was there, I was frequently asked for my mother's maiden name to be used on my paperwork, but I was quite resistant given I had a couple of accounts (banking primarily) that I could not change the security questions for and made use of "mother's maiden name" as a "secure answer".

I've lost track of the ways that broke peoples software, while I was over there, and started giving my middle name or asking them to double my surname. One place was unable to send me any mail for a while until they figured out that the software would silently skip "incomplete" accounts when generating monthly invoices. One place would inject "null" so I got mail to that was "null-Surname". One place just wouldn't allow them to create my records without a second surname.