We confess all on Facebook. The whole world knows what we ate for lunch and what we think about political or social issues. But we don't tell the world how much we earn or owe.
The money taboo has a huge impact on families in particular. It causes marital disputes and leaves children unprepared for the big wide financial world.
Our values shouldn't be based on money. But plenty of people rank others on their apparent financial success.
I overheard a conversation in a cafe in which a local complained a third party was obsessed about how much everyone spent. He apparently judged people on the $50,000 kitchen or $200,000 extension.
I don't know anyone who admits how much they earn. They feel ashamed if they don't have as much as the Joneses or embarrassed that they have much more.
The money taboo isn't just about envy or avoiding ridicule. We also lose money. We're too embarrassed to ask prices - for funerals, for example. We may be reluctant to ask the dentist or the car repairer what the final bill will be. And we don't ask enough questions about investments, which sometimes leads to being scammed.
The money taboo lands people in all sorts of hot water - especially in the Family Court. When they married they probably had intimate sexual knowledge of each other, but may not have known their partner's true financial situation. Ex-spouses find they had no idea what the other partner had been up to with money.
Couples' money discussions or lack thereof may represent a host of other difficulties in the marriage that the partners are unaware of or have difficulty addressing, says Mark Thorpe, head of the psychology department at AUT University.
We focus on whether we or others have enough money - or otherwise. "This focus may represent to us a concern about whether we have enough love, support, power, prestige, safety, food, nurturance, masculinity, worth, sex, competence, freedom, etc," says Thorpe. "An avoidance and inhibition about talking about money may therefore reflect the same difficulty about talking about these other important life issues."
The time when the money taboo is finally dropped with a couple is in the Family Court, at which point it explodes, says Thorpe. "Then suddenly all the resentments and unresolved issues from years ago show their nasty face in the guise of fighting about money."
Banking Ombudsman Deborah Battell sees case after case in which couples haven't been open and honest about money. "Lack of discussion about finances by couples, families and business partners leads to a substantial number of complaints," says Battell.
"It is not unusual for us to receive complaints from people who have been surprised by how little is left in accounts - whether these are joint accounts with partners, trust accounts, accounts managed by family on behalf of elderly parents or other similar situations," says Battell. No one discussed what was going on.
There are ironies about the money taboo. One is that talking about money creates conflict, but so does not talking about money.
Another is that money is also avoided as a topic with children, who miss out on a financial education.
Money does all sorts of strange things to us. One example cited by American psychologist Richard Trachtman is of fathers who deprive their children of contact because they are pursuing money as an immortality symbol. We've all seen it, the man - and I'm sure there must be women - who pursues more and more money even though he's comfortably off. The more money he gets the greater the chest beating and sometimes the less his child sees him.
Thorpe poses the question that the money taboo may have a hand in the well-documented tall poppy syndrome in New Zealand, the great Kiwi clobbering machine. "The press is full of articles criticising CEOs earning 'unwarranted' and 'unfair' salaries, but are we open about what we earn and how we spend our money?"
As Battell suggests, the taboo applies to the older generation as much as it does to families still making their way in the world.
As it transpires the elderly are some of the worst hit by the money taboo. Financial abuse of elders is rife in New Zealand and is most often carried out by members of the family. If siblings or other relatives never talk about money with the older person and each other they may never realise what is happening.
Yet there are money issues people are willing to brag about.
Within minutes of meeting, a complete stranger at a children's cricket event this summer was boasting that he'd made $200,000 profit on an investment property in Beach Haven. He hadn't asked my name so wouldn't have known what I did for a job.
It's not the first time I've endured this type of conversation. The next time it happens I'm going to ask the person how much they earn. I bet there won't be a reply.
My gut feeling is most people would be happier to reveal their level of debt than what they earn - even though the debt is something they should be embarrassed about. It seems to have become a badge of honour in our society.
Yet if more people would talk about how they got into debt and out of it - if they had - there would probably be fewer debt problems.
I asked Thorpe for ways to overcome the money taboo. In an ideal world we can talk about life's important issues - one of which is money. If we want to overcome this taboo we need to reflect.
The first thing to do is to trace the origin of the inhibition to its personal, social, and cultural roots, says Thorpe. Remember and think about our childhood experiences of money.
"How was money discussed or avoided in your youth?" asks Thorpe. "Were there open discussions on money, business plans, or debt around the dinner table? Was money never mentioned - as if it was something dirty and to be avoided? Did your parents fight about money? Were the fights ongoing or did they only erupt at times?
"Was there someone else in your extended family, an aunt or uncle, who spoke about money with ease?" says Thorpe.
A friend of mine ended up in discussion recently with her nieces and nephews who think she's rich - despite being a single parent.
She compared the choices she had made at their age (studying, working, saving and delaying children until her 30s) with those of her nieces and nephews. They chose not to study, had children in their teens and lived on benefits. Hopefully some of that discussion from auntie about life being full of choices will sink in.
Thorpe says to look at the basic templates laid down in childhood and consider how you still adhere to them. Once you have a clear idea about your style of thinking about and talking (or avoiding talking) about money, you can set about changing the pattern.
Thorpe recommends listing five things about money that you struggle to talk about. Rate the five in order of difficulty to discuss.
Start with the easiest. "Take a big breath and talk to your partner or friend about the topic. It may help to warn the person that you want to talk openly about difficult emotionally laden money issues."
Once the first topic has gone well, move on to the next easiest topic or issue. Gradually work your way up to the most difficult topic, says Thorpe.
It would be useful if your partner is doing the same process and you take turns in talking. Don't rush it; space it over a few weeks.
There is surprisingly little research into the money taboo and its emotional effect on people's lives. One of the reasons for that, says Thorpe, is that psychologists are particularly prone to suffering this taboo themselves.
Brian Gaynor's column will return next week.