Louis Armstrong was quite wrong: a kiss is never just a kiss. When shared between parent and child, as Victoria Beckham has found out, it's a pout-rage.
After posting a gorgeous picture of herself kissing daughter Harper to mark her fifth birthday, the designer has been inundated with complaints online. Her alleged offence? Having kissed said daughter on the lips.
While some of the critics brandishing their virtual pitchforks were determined to find the picture sexualised in some way, most described it as plain "weird" or were, quite honestly, perplexed by it.
But almost at once, other mums stormed to defend Beckham by posting pictures of themselves kissing their children, with hashtags #loveislove and #letchildrenbechildren. At the school gate, opinion is firmly on VB's side, with one mother of four telling me that her seven-year-old daughter adores giving big snoggy kisses on the lips. Her elder girl, who at 11 is entering puberty, is more circumspect, but not averse to a quick peck. "I love that we kiss on the lips," the mum says. "I was brought up in a demonstrably loving family with a very tactile father. I'm proud to pass that on. It's the ones claiming to be offended who need to think again. The problem is in their heads and imaginations, not in reality."
But we are all different. My own family are naturally more reserved, so I am a hugger and a tickler, but not a lip-kisser. It doesn't cross my mind. Perhaps I am the weird one? Although I don't get offended at home time when rows of cute little daughters (but fewer sons) pucker up in the playground for a kiss from Mum or Dad.
Which makes you wonder: would the criticism have been different if the kiss on the lips had been shared between David (an openly devoted dad) and Harper? Probably not. A snap of Harry Connick Jnr kissing his eight-year-old daughter goodbye on the lips five years ago inspired a fair amount of negative comment, including some from US psychologist Dr Charlotte Reznick, author of The Power of Your Child's Imagination, who warned that such kisses can muddle a child.
"If you start kissing your kids on the lips, when do you stop?" said Dr Reznick, associate clinical professor of psychology at University of California Los Angeles. "It gets very confusing. As a child gets to four or five, and their sexual awareness comes about, the kiss on the lips can be stimulating to them.
"Even if that never occurs to a child, it's just too confusing. If Mommy kisses Daddy on the mouth and vice versa, what does that mean when I, a little girl or boy, kiss my parent on the mouth?"
Hampshire-based psychotherapist Jennie Miller, who specialises in relationships, agrees that whether we like to admit it or not, there is more to a lip-kiss than parents may want to accept. "The reason why some people feel uncomfortable with this is because the lips are a really powerful erogenous zone," she says. "That's why adolescents kiss for hours, particularly if they are not having full sex.
"So younger children may feel that being kissed on the lips is pleasant, even though they have no idea that it is to do with their future sexuality."
Miller emphasises that these type of parent-child kisses are not a bad thing, but adds: "You just need to understand why a child wants to do it. Then you can draw an appropriate boundary around it by explaining that you kissing Daddy is different to you kissing children.
"That could mean talking about puberty, and why lip-kissing feels nice. That can lead into a sensible and subtle conversation about permission - that they have the right to refuse if someone else wants to kiss their lips; that the mouth can be a no-go area."
Of course, most children will make the break from maternal or paternal lip-lock by themselves - possibly just before puberty, certainly by the time they start slamming doors and despising their parents for breathing.
But if parents want to make the decision, they can follow Dr Reznick's advice and stop as soon as a child gets to school age or it feels awkward.
Unless they want to be like 62-year-old US American football coach Bill Belichick, who was caught on camera lip-kissing his 30-year-old daughter Amanda after his team won the Superbowl last year. Which, while clearly just a moment of unalloyed happiness for them, felt extremely awkward for everyone else.
The Telegraph, London