[ubersoldat2k7]

It's normal interrogation techniques. They ask normal stuff to see if you lie or you get nervous. Just watch any of those airport security shows on TV to see how many people who end up smuggling stuff fail to answer those simple questions or change their story several times during the interrogation process.

[onetimemanytime]

I understand that...that's why they ask 100 times the same question in detective interviews. Truth is the same, but if you're lying you might refine it and eventually forget so you invent a new one.

So it's not to prove that you're John Doe but to see if you have anything suspicious with you or if you're up to no good.