Richard di Natale is the parliamentary leader of the Greens, and he is also a trained scientist.

He is not the first in the position; the party’s founding father, Bob Brown, is, like di Natale, a qualified medical doctor.

But is it is fair to say that Brown is a more passionate, emotional individual. He observes and respects the scientific method, but if its conclusions go against his political instincts, he is willing to set them aside.

Di Natale is more hard-headed: evidence is evidence, science is science, and it must be pursued whether convenient or not. And it is that uncompromising rationalism that has brought him into conflict with many of his followers.

Too often the Greens accept science only when it suits them. There is no doubting the science of climate change, for instance: the world is warming, the seas are rising, the glaciers are melting, the weather is getting more extreme. Sceptics, denialists, log rollers and conspiracy theorists must be rejected with scorn and loathing.

But the Greens are far more divided about science when it comes to fluoridation, or, far worse, vaccination; and a large majority are firmly against all forms of genetic engineering, which is di Natale’s current problem.

Genetic engineering is not a new idea; the Incas bred the useless (in human terms) guanacos to produce llamas and alpacas, and turned the poisonous lupin into a nourishing grain. Similar scientific selection has been routine for many generations.

But gene technology, although no more than a logical extension of selective breeding, is considered something different, and with some justification; although we are assured that the human genome is about 60% identical with the genome of a banana, there is something mildly discomforting about the idea of inserting, for instance, the gene of a fish into that of a tomato.

This, the Greens assert, is unnatural; and so it is. But that is just the point. All applied science involves the manipulation of nature: it is about changing things, not leaving them as they are. From the scientific perspective there is no real difference between splicing one gene into another genome and adding carbon to iron to produce steel. If the process improves the product, it is worth doing.

There are other concerns about genetically modified organisms (GMOs): patents and monopolies exploited by giant corporations such as Monsanto, and the dangers of limiting crops to monocultures, especially in vulnerable agricultural economies. And then there is the economic angle: so-called “organic” produce may be more expensive than GMO products, but it can command a very lucrative market.

These matters should be and must be taken into account. But food safety has been rigorously and exhaustively tested and has been given the all clear by an overwhelming consensus of research. The science, as they say, is in; which means di Natale is in with it.

He is unwilling to push the issue too hard – he cannot afford an open break. But he is too honest to be comfortably silent – and so, too honest for his party, and perhaps, for the current political system.