SINGAPORE - A few of us were at our friend S's place when he grabbed one of his twin boys in a bear hug and planted a kiss on his head. Then, realising it was the older boy, he said playfully: "Oops, wrong one."
Scandalised, we stared at him.
His wife had long told us that the younger twin was his darling, but we were surprised he made no attempt to disguise his feelings in front of the pre-schoolers.
The topic of favouritism is a contentious one: Most people believe it exists, but most parents will flat out deny it.
Two years ago, American journalist Jeffrey Kluger stoked the debate - and no doubt tore open scores of old wounds - with a cover story for Time magazine titled Why Mom Liked You Best: The Science Of Favoritism.
"It's one of the worst-kept secrets of family life that all parents have a preferred son or daughter," he wrote.
He cited as evidence a 2005 study by researchers from the University of California, Davis, who followed about 400 pairs of siblings and their parents for three years, and concluded that 65 per cent of the mothers and 70 per cent of the fathers were partial to one child.
Mr Kluger did not explain how 65 or 70 per cent worked out to be "all" parents. But in his 2011 book, The Sibling Effect: What Bonds Among Brothers And Sisters Reveal About Us, the father of two reiterated that "95 per cent of parents in the world have a favourite child - and the other 5 per cent are lying".
I have been using this as ammunition against my poor husband, even as I pooh-pooh the second half of the exaggerated statement and insist I am scrupulously fair.