If you don't feed your children meat, one day you may have to confess: "Honey, I shrunk the kids."
That's according to an American scientist who says you risk damaging your children and stunting their physical and mental growth if you withhold meat and other animal products from their diet.
What's more, the damage may be permanent, says Professor Lindsay Allen, director of the US Agricultural Research Service's Western Human Nutrition Research Centre at the University of California.
She reserves special condemnation for parents who feed their children a vegan diet. Veganism is described as "not just a vegetarian diet, but a way of living that seeks to exclude all animal products including eggs, milk and cheese".
Allen says there's "absolutely no question that it's unethical for parents to bring up children as strict vegans". She concedes that adults can avoid animal foods if they take the right supplements, but the risks are "too great for children".
Not surprisingly, this view has provoked outrage among nutrition specialists and vegetarian and vegan parents, among them former Beatle Sir Paul McCartney, a vegetarian for 20 years along with his late wife Linda, who brought out a successful range of meat-free foods. All his children are vegetarian, and he points out they are all fit, healthy and "no shorter than others".
After media reports of Allen's research last week McCartney called the BBC to protest. He said there was consensus among doctors on benefits of a vegetarian diet, and Allen's views were likely to be "engineered by livestock people who have seen sales fall off".
Allen reached her conclusions after conducting a two-year study of 566 impoverished rural Kenyan children. She found that when just two spoonfuls of meat were added to the children's starchy staple diets each day, they showed dramatic improvements (80%) in muscle development and mental skills. They became more active, talkative and playful, and showed more leadership skills. Another group given a cup of milk a day or an oil supplement containing the same amount of energy also showed improvements of 40%.
Allen presented her findings at the recent annual meeting of the American Association for the Advancement of Science, in Washington. She said animal source foods had nutrients not found anywhere else and were essential for young children and pregnant and lactating women. Withholding these foods during that time was "unethical as empirical research showed the very adverse effects on child development".
She has some support from reputable quarters.
Dr Alastair Sutcliffe, senior paediatrics lecturer at University College London, was quoted as saying human ancestry shows a natural diet includes meat and is likely to produce a taller, stronger child.
He respects adults' ethical decision to eat a vegan diet, but says it should be "very carefully considered if that is the right decision for a child". He says a vegetarian diet including dairy products would "probably be fine for children".
Yet there are gaping holes in Allen's argument, and you don't have to be a research scientist to see them. It's also tempting to think, as McCartney does, that somewhere, somehow, the meat industry is behind this research.
After all, the vegetarian movement is growing worldwide, and that is making powerful vested interests in the meat industries feel ever more lean and mean.
Research shows a vegetarian diet can and does provide all the nutrients necessary for a child's growth and development at all ages. Allen errs in extrapolating the results of a study on children in a developing country, on an inadequate diet, and generalising to the developed world. But she also commits a very basic error of logic: she adds one variable to the children's diets - in this case meat and other animal products - and then concludes it is optimum simply because it provides benefits.
Cape Town homeopath and naturopath Dr Philip Sherwin says that reasoning is fallacious. Meat has nutritional value, and it's not surprising the children showed some improvement because their diets were so deficient to begin with, he says.
However, fresh fruit and vegetables, nuts and seeds also have nutritional value. They are power houses of vitamins and minerals and are likely to produce the same improvements when added to a grossly deficient diet, he says.
To exclude them, Allen would have had to add them as a variable in her study or do a parallel study.
Sherwin says vegetarian foods are likely to be better and cheaper for children than animal products, particularly if grown organically.
They don't have the health risks associated with meat and other animal products.
Nutrition specialist Dr Charlotte Prout Jones agrees. She says if Allen's study proves anything, it is that a starving child will benefit in the short term from any food with some nutrition in it.
Prout Jones runs the Life Science in Chartwell and specialises in fasting and natural food and juice therapies to treat a range of serious illnesses.
Life Science is an international movement that began in the US more than 100 years ago, and is the study of human well-being and nutrition in all its facets.
It is based on veganism as the ideal diet, because those are the foods for which humans are "naturally adapted", Prout Jones says.
For starters, plant foods have far more of the enzymes needed for digestion of food than animal products. Meat is also not a particularly good source of protein because the protein it does have is coagulated and the amino acids it contains are not freely available to the human body, she says.
Modern animal food production methods involve extensive use of hormones, antibiotics and other chemical additives. Prout Jones says meat eaters are showing a disturbing increase in hormone-related diseases including young boys growing breasts during puberty.
Milk products also increase the risk of mucous-related diseases such as sinusitis and throat infections.
The reality is that starvation in the world is not a result of lack of food, but bad management and distribution, Prout Jones says.
And if there's any diet that is unethical, it is one containing meat.
She says the "meat habit" is a major cause of environmental destruction. About 85% of grains in the world are grown not to feed people, but to feed animals killed for food.
The British Dietetic Association says Allen's findings are not applicable to vegan children in the developed world, and there is no evidence that vegan and vegetarian children in the UK have suffered impaired development.