LONDON (Reuters) - Forget sex and scandal. Science is now splitting British royalty as family members engage in a lively debate over genetic modification.

On one side: Prince Charles -- the man who used to talk to his plants and is now one of the country's most respected organic farmers.

On the other: his no-nonsense younger sister Princess Anne and their notoriously outspoken father, Prince Philip.

Philip stirred the pot on Monday night by defending GM foods from the sort of attacks being launched by Charles and playing down the risks associated with so-called ``Frankenstein foods.''

Queen Elizabeth's husband was quoted as saying at an engagement at Windsor Castle that man had been tinkering with nature ever since he began selective breeding:

``What people forget is that the introduction of exotic species like, for instance, the introduction of the gray squirrel into this country is going to or has done far more damage than a genetically modified piece of potato.''

Charles has often found himself at odds with his father, an ex-military man who does not share his son's interests.

The queen has not chimed in in public, but may at least be pleased that family squabbles have taken such a highbrow tone.

The row also shows once-remote royalty more in touch with the public, with GM a talking point from shop floor to farmyard.

Many supermarkets have stopped selling GM produce and environmental protesters have wrecked whole fields of GM crops.

Last month the government was forced to admit that farmers had unwittingly planted seeds contaminated by GM crops in a case that detractors said proved the technology was out of control.

Sharp-tongued Princess Anne has little time for such ''green'' voices, putting herself firmly in the pro-science camp.

Just last Sunday, in remarks seen as a swipe at her brother, Anne told the Grocer magazine that those who were opposed to GM foods were guilty of a ``huge simplification.''

Yet her big brother has found rare fulfillment in his long wait to take the throne by embracing the outdoors and turning away from conventional farming to plough an organic furrow.

Long opposed to GM foods, Prince Charles used a lecture last month to issue a wake-up call for the sake of the planet.

``We need to rediscover a reverence for the natural world, irrespective of its usefulness to ourselves,'' he said. ``If literally nothing is held sacred anymore, what is there to prevent us treating our entire world as some 'great laboratory of life' with potentially disastrous long-term consequences?''