Australia and New Zealand have been in an intense relationship, demonstrating extreme sibling rivalry and affection, since the 19th century when ships began sailing between the two countries, taking the inhabitants of one and depositing them in the other. As colonies, you might say we were joined at the ship.
We have numerous differences and are fierce rivals over matters momentous and trivial but, finally, share qualities which are unique to our two countries and more important than anything that divides us.
To some extent, our rivalry unites us, as with many duos who drive each other crazy but can't seem to get away from each other - we're like the Simon and Garfunkel of countries.
New Zealanders and Australians don't have to look hard to find a personal connection with each other's country. My case is probably not unusual. I have links I should probably make plain lest anyone think I'm favouring one side over the other.
I have had an Australian stepmother since 1965, an Australian half-brother since 1967 and spent two periods living and working in Sydney before realising that everyone has a home where they belong and mine is here.
Our differences are indeed many. They have a population of 22.5 million, about the same as India's capital, Delhi. We have a population of 4.5 million, about the same as Barcelona. Their landmass is 29 times greater than ours.
Accordingly, they think bigger is best and we think small is beautiful.
Our differences are also often symbolic of our different characters. Their land is wide and brown, like a cow pat. Ours is thin and green, like a joint. They like visiting here. We like living there.
They have given us the Queensland fruit fly; we put up with a ban on apple exports for nearly a century because of the mere possibility we might give them fireblight. They took part in atom bomb tests in the middle of their country; we took part in nuclear protests in the middle of the Pacific Ocean. We gave them Derryn Hinch; they have given us back Paul Henry.
Their prime minister, an enthusiastic surf lifesaver, wears Speedos where people can see him. Our prime minister has been considerate enough not to share with us just what he wears on the beach.
If you think 120 is a lot of MPs, check out Australia's Parliaments. Their system of government is complex, cumbersome and expensive. It has states and territories that have their own capitals and parliaments working in tandem with the national government which has a two-tier system and is based in an eerie city that was invented solely for it.
Their method of proportional representation, the single transferable vote, means you can end up electing your second or third choice of representative.
If Australians are slow to acknow-ledge the New Zealand contribution to their economy and culture it may be because it is so vast. Prominent figures cover all areas of public life in high and low culture, including musician Keith Urban, actor Russell Crowe, broadcaster Brian Henderson, politician Joh Bjelke Petersen, actress Rebecca Gibney and satirist John Clarke.
Many New Zealanders are in senior positions in large Australian companies. Conversely, many Australian companies are in large positions in the New Zealand economy, our banks in particular.
If New Zealanders are reluctant to acknowledge the contribution Australians have made here, it's because it's so hard to find. You don't have to look far to learn that our great Prime Minister, Michael Joseph Savage, was born in Tatong, Victoria. After that, if you're on the hunt for a prominent Australian on this side of the Tasman there's quite a long gap until you get to, um, Alison Mau.
Sporting rivalry is easier to deal with because it offers results - winners, losers and league tables tell their own story without fear of contradiction. Australia contributes more than its fair share to this area, recently having introduced the concept of the sore winner. There was a brief and, in retrospect, surreal period where we sought to dominate each other in an internationally obscure yacht racing event.
When it comes to recognised international measures of excellence, there's not a lot to choose between the two nations. They have 15 Nobel prizes, we have three. So they have five times the number with about five times the population. At the Oscars, we have won 17; they have 47.
You can carry on playing this game forever and we almost certainly will. If the phrases "punching above our weight" and "per capita" didn't exist, they would have had to be invented so Australians and New Zealanders could talk about each other.
But it's the field of music that sees our transtasman cousins practising cultural appropriation at its most shameless. Mi-Sex, Crowded House, Split Enz, Dragon - all essentially New Zealand bands - were claimed as Australian. But when expat New Zealander Richard Wilkins revived the term "Austra-lasian" to describe Lorde so Australia could have a piece of the singer, New Zealand collectively cleared its throat, sat up and said, "I say, do you mind?"
The strength of the rivalry indicates just how close the emotional bond is. You don't get this het up unless you care about each other. It's hard to think of two other countries that would carry on for decades an argument over which was the first to produce a meringue-based confection. And because it will probably come up again his weekend, it's worth mentioning that, like the pavlova, the earliest printed record of Anzac biscuits is also from these islands.
A lot of the bickering uses themes that are common between any two competitive countries. The foul charge of a propensity to engage in sexual intercourse with sheep, to which Australians resort when they have lost all other lines of argument, has also historically been made by the French against the Belgians and the English against the Welsh.
When you get to the sheep-shagging, of course, you're close to the bottom of the
barrel, a region where Australians have long felt comfortable. I've always found it endearing that they should feel entitled to find amusement in the way others speak. It's hard to see why "fush and chups" is more inherently mirth-making than "feesh and cheeps".
And like any other rivals, we are quite capable of getting mawkishly sentimental about each other, especially in London pubs when we're in our 20s and watching either of our countries beat the Poms at anything. This week's headline "Anzac spirit averts
Poppy crisis" also demonstrated that tendency to engage in cheap sentiment.
Stretching back before World War I and the original Anzac Day, New Zealand and Australia developed in parallel as colonies of the Mother Country, and therein lies the roots of some of our most significant differences and similarities.
Although it's satisfying for Pakeha to assume an air of moral superiority over our white Aust-ralian counterparts in our relative attitudes to and treatment of the Aboriginal and Maori populations, it's not quite so clear cut. Australia slaughtered Aboriginals when they got in their way, neglected them when they weren't, excluded them from participation in the life of the country as a whole then returned to wholesale persecution when they happened to be in the way of valuable minerals.
But it's not hard to make the case that New Zealand's colonists did something similar, purloining land and resources in more genteel, respectable fashion, with legalistic sleight of hand.
New Zealand and Australia were colonised by refugees from the rigid class structures of England, which compelled them to lead only the lives they were born into, with little chance of bettering their position.
New Zealand and Australia gave the chance for a new start. A key difference is that the New Zealanders chose to move here; the Australians were sentenced there.
New Zealand's English settlers were utopians at heart - the Australians were convicts and their keepers - not all of them, but enough for that to be a formative influence on the national identity, which prides itself on being rowdy, rascally and disdainful of authority.
Once they had done their time, the freed convicts in many cases reacted by making themselves uber respectable. They aped their English betters, even down to the houses they chose to live in, squeezing their terrace homes on to small plots instead of expanding into the vast spaces available.
New Zealand's utopians put their minds to creating a better society, leading to such revolutionary moves as women's suffrage, pensions and the apparatus of the welfare state.
Psychologically, those colonists had to deal with what the great Australian historian Geoffrey Blainey called the tyranny of distance. We are just so far away from anywhere.
Most of those who sailed across the world to these lands were certain never to see Britain again, which is why, as the decades went by, making trips "home" became so important.
Thus isolated, they developed the sense of independence that gave birth to the myths of self-reliance and the number-eight-wire mentality. We couldn't go anywhere else for solutions, because there was no anywhere else here.
This also bred the egalitarian spirit that was shared by both countries. We were all in this together.
Although it is not so strong now, it has left an enduring legacy.
If you want to do anything at all, you're likelier to get a chance to do it in New Zealand or Australia than in just about any other country where bribery or membership of the old boys' club or accidents of birth are the accepted ways to get ahead. That's how we do things. And that's why we understand each other so well.
Just don't ask the Australians to make box-office, record-breaking, 17-hour fantasy movie trilogies - they wouldn't know where to begin.