The reason for the cutoff of ‘86 is because our laws on citizenship changed that year. Before then, we used ‘jus soli’ (right of soil), which meant that if you were born in Australia, you were Australian. My father was born here to immigrant parents and was granted citizenship at birth. It also still works that way in the US. We now use the system of ‘jus sanguinis’ (right of blood) which means citizenship is transferred by descent. This is the system that’s used in most european countries. Everyone born in Australia, even the child of a tourist, is issued an Australian birth certificate, so it no longer proves citizenship.

The major flaw in our system is that, outside of citizenship certificates, we don’t have anything other than passports that proves you’re a citizen. Most people only get them when they’re planning to travel overseas, and they cost a lot of money. European countries have government ID cards to prove citizenship because international travel is a lot more common there. But many Australians never travel overseas, and it can stretch back for generations. That’s just not the background politicians usually come from.