All parents are supposed to think their children are attractive - but Canadian researchers claim that "ugly" offspring are treated differently.
Do parents treat their children according to their looks?
A team from the University of Alberta looked at how much care parents took to ensure their children were safe while shopping.
They claim children they assessed as less attractive were more likely to be neglected.
But other experts warned the findings were not backed up by other research.
The team followed 426 parents with their children, aged two to five, in a supermarket for 10 minute periods.
They looked at whether or not the child was buckled into the trolley, and how often they wandered more than 10 feet from their parents.
The children were also rated on a 10-point scale of attractiveness
They found that only 1.2% of the children they judged to be least attractive were buckled in, compared with 13.3% of the most attractive.
So-called 'homely' children were also allowed to wander off more often.
Dr Andrew Harrell, who led the research, said his findings had not been welcomed by parents.
He said: "Most people are upset that attractiveness would even be a factor - they certainly don't think it is.
"If you give them a questionnaire, they'll say 'No, I love all my kids and I don't discriminate on the basis of attractiveness'.
"The whole point of our research is that people do."
He said the probable explanation was Darwinian - parents unconsciously lavish more attention on attractive children because they carry the best genetic material.
"Attractiveness as a predictor of behaviour, especially parenting behaviour, has been around a long time."
But Dr Nick Barlow, of the British Psychological Society, said attractiveness was a subjective assessment.
"It's all in the eye of the beholder."
"If you look at children with Down's syndrome or a cleft lip, parents are often over-protective, so there's no sign of rejection there.
"This is a dangerous report because people talk about designer babies. If we're not careful, scientists will be looking out genes for high cheekbones or blue eyes."