I much preferred it when merchant bankers left you in no doubt that they were motivated by greed.

At least you could trust their instincts then, if not their principles.

Malcolm Turnbull’s son Alex followed his father into merchant banking — and what an absolute banker he appears to be.

The chip off the old block is asking voters in the family bolt hole of Wentworth to deny support in this weekend’s by-election to the party that made a Turnbull into a prime minister.

You could understand if his reason was to seek revenge on those who snatched away his father’s glittering prize.

But no, the Singapore-based fund manager claims his concerns are based on helping save the world from climate change.

So, if that’s true, he also seems to be mirroring his father’s famous political ineptitude. However, his real motivations are likely to be less altruistic.

Shortly after his father was rolled, young Turnbull went public supporting his friend Tim Murray, the Labor candidate, retweeting one of his campaign funding pleas.

“Best bang for the buck you’ll get in political donations in your life,” Turnbull Jr tweeted, showing that he even sees electing an MP as an investment.

“Tight race, tight margin for government, big incremental effect whatever happens. If you want a Federal election now this is the means by which to achieve it.”

In other words, he’s suggesting the Government that his father almost single-handedly caused to have just a one-seat majority might fall rather than run its full term. It would be great to know what his grandfather, the venerable former Liberal MP Tom Hughes — who once threatened anti-conscription protesters outside his home with a cricket bat — thinks of such tactics.

Then again, Hughes was sacked as attorney-general by Australia’s feeblest prime minister, Billy McMahon, before retiring hurt from politics and making squillions at the bar. So he has his political axes to grind, too.

Turnbull the Younger is showing his father’s historic uneasiness with the Liberal Party — after all, Malcolm first sought pre-selection from Labor — claiming it has been taken over by “extremists on the hard right”.

That seems a strange description of Mitch Fifield, Mathias Cormann or even Michaelia Cash, the ministerial deserters who crystallised the former prime minister’s fate.

Last week, young Turnbull put out a video on social media calling for the Liberals to be sent a message about climate change, apparently in response to the latest Intergovernmental Panel on Climate Change report, although he has been banging on about the issue for some time. He has been provided with a stream of unquestioning reports by Fairfax, the ABC and the Guardian. Not one mentioned his father’s own measuring stick of 30 losing Newspolls.

Days after the coup, he claimed “rent seekers” backing the coal industry had brought down his father.

That seemed to fly in the face of the older Turnbull’s very public insistence that AGL keep open its coal-fired Liddell power plant in NSW, which would ensure mines were operating.

Young Turnbull claimed the coal barons “have their hooks into the Liberal Party ... which has no money”.

Well, we know the Liberals are broke because his father had to chuck in a lazy million to keep them afloat for the double dissolution election he called too late and nearly lost.

But if the contention were true, surely the party would have plenty of money as its reward for dancing to the coal industry’s tune?

It gets worse. Back to young Turnbull’s latest video intervention in Wentworth: “The IPCC report, frankly, was terrifying if you read the whole thing. It’s seemingly insane to me that we could not be doing something about this, and soon”.

Frankly, I wouldn’t want anyone who swallowed that report whole — and was terrified by it — to be handling any of my money. Even if Australia cut our carbon emissions to zero it would have negligible effect under climate change theory.

Those with long memories might recall it was the father’s admitted adherence to daughter Daisy’s belief that the Turnbulls could save the world from global warming that led overheated Liberals to sack him as their leader the first time around in 2009 when he was supporting Kevin Rudd’s emissions trading scheme.

Politicians who take policy advice from their children deserve everything they get.

But Malcolm may have learnt from his first mistake because he apparently doesn’t agree with his son’s views now. Well, that’s what Prime Minister Scott Morrison says:

“I disagree with Alex. His father disagrees with him, too.”

So how realistic is it to try to turn this by-election into a test on climate change policies?

Actually, it’s not as silly as it might sound. Wentworth has the highest concentration of high net-worth individuals in the nation, people who have less of the real-world economic and social pressures faced by ordinary Australians.

This is a classic “doctors’ wives” electorate where voters have the luxury to indulge themselves in their pet issues, rather than those that might be in the national interest.

It is full of Mr and Mrs Harbourside Mansions and a scattering of Bollinger Socialists who have probably put their knees under nearly as many billionaires’ tables as Bill Shorten.

Young Turnbull grew up with these people and must think he feels their moral pain, in a Rudd-like way:

“We’re going to have an election in 12 months anyway, so if you want to send a signal as to which way the Liberal Party is going, and your displeasure with where it’s going, then this is your opportunity.

“Don’t vote for the Liberal Party in the Wentworth by-election. If you want to pull the Liberal Party back from the brink, it’s the one clear signal you can send.”

No one would be surprised that Turnbull the Lesser was advocating for retribution against those who denied his father twice.

But, apparently, that’s not the case. It’s all about the planet.

Merchant bankers and fund managers love carbon trading schemes because they represent another opportunity to make money. Whether they reduce emissions is secondary.

Even the clever people in Wentworth need to be wary when merchant bankers appeal to them about saving the world.