A photo which appeared to show Donald Trump kissing his daughter Ivanka on the lips has sparked a debate on social media.

Exactly how should a father greet his daughter?

The pair were touring a factory in Pennsylvania to publicise tax changes when they were snapped.

A video of the event later showed that it was actually a kiss on the cheek.

But it sparked discussion on whether a full-on kiss between parent and child was right or wrong.

The incident echoes a debate last year when David Beckham was shown giving his daughter Harper, five, a kiss on the lips.

Beckham was criticised over parental boundaries.

But in a Facebook Live discussion he reportedly said: “We want to show our kids love and we protect them, look after them, and support them, and we’re very affectionate with them.”

And the former The Only Way Is Essex star Sam Faiers was drawn into the discussion.

She appeared in a TV show about the birth of her baby called The Baby Diaries which showed her partner Paul Knightly kissing his mum Gaynor on the lips.

He was criticised on social media and Sam reacted by sharing a picture of herself kissing her baby son Paul on the lips, the website Made for Mums reported.

“It’s safe to say most parents kiss their children on the lips when they’re small. They’re just so scrumptious, why wouldn’t you?,” said an article on the site.

“But at what age do you stop?”

Parents have shared their opinions on social media sites such as Mumsnet.

Views vary with many saying it’s acceptable to kiss very young children on the lips.

But many also say it’s a habit to get out of as the children get older.

One mum posted: “Not normal. I think lips are only for romantic-type kissing.”

But another said: “Totally normal here.”

The consensus on message boards, however, is lip kissing is for husbands and wives.

Many mums spoke of turning their heads if anyone other than a spouse came in for a lip kiss.

Others admitted kissing their children - both girls and boys - on the lips.

But most said there was a limit to what was acceptable while acknowledging that different families had different ways of dealing with the issue.

Some families are touchy-feely while others are not.

poll loading

Is it OK for parents to kiss their children on the mouth?

“I have a lovely photo from my wedding day of me and my Dad lip-kissing. People have ewww-ed at it but it’s just normal in our family,” said one posting.

It might just be British reserve, some say, with different traditions in different countries.

Comments by Dr Charlotte Reznick, a child and educational psychologist at Californian university, occasionally go viral on the internet since she was first quoted in 2010, reported the Mirror.

At the time, she said: “If you start kissing your kids on the lips, when do you stop? It gets very confusing.”

But other experts disagree.

Dr Paul Hokemeyer, a family therapist, disagrees with the theory, telling Yahoo Parenting: “It’s important that parents keep and maintain boundaries with their children, certainly, but in terms of expressing affection this feels within the realm of normal,” the Mirror said.