The Internet has been tittering over some titillating shots of a supermodel, her son and - pardon my language - her tit.

American supermodel Stephanie Seymour, 42, was recently photographed on a beach, kissing and cuddling her 18-year-old son, Peter Brant II.

And, in some shots, it looks as if he has one hand on her breast, while planting his lips almost on hers.

I'm all for telling people to "get over (t)it".

After all, the line between what is acceptable and creepy, what is innocent and sexual, is drawn differently - depending on your cultural, social, political, economic and generational standpoint.

It also depends on how hot your mummy or your son is.

How we receive the image of Seymour and her son embracing has already been tainted by the associations her famous bikini- clad body carries.

She is, after all, a former girlfriend of hair-metal rocker Axl Rose, immortalised as a minxvirgin bride in Guns N' Roses' November Rain video.

I suspect, even if she were to be handing out alms, one look at her in a swimsuit and the mind goes into customary sexual overdrive.

What more when she is clasped in her teenage son's arms?

Compounding this visual conditioning, in our celebrity culture, are thousands of similar paparazzi shots of yummy mummies canoodling with younger lovers on beaches: Just think Halle Berry, 44, and her former boyfriend, Gabriel Aubry, 34; or Demi Moore, 48, and husband Ashton Kutcher, 32.

See enough of such pictures, and the eye recognises patterns that lead the brain to jump to conclusions.

My slightly unorthodox take on the whole affair is that it signals the artificial divide that society places between a safely asexual image of motherhood and the rather-more-complex physical reactions a mother's body experiences.

A few years ago, when my friend mentioned "orgasmic births" (Google it, if you dare), I could not quite believe my ears.

Similarly, my eyebrows shot up when I came across online discussions about sexual pleasure from nursing a baby, when I was a new mum looking for information on breastfeeding.

While I'm not passing judgment on whether these things are right or wrong, it does help to remember that every mother and child, and their relationship, is different.

Since the photos surfaced more than a week ago, Peter Brant II - the eldest of three children Seymour has with her billionaire husband, Peter Brant - has lashed out against detractors via his Facebook account.

He said: "My mother and I are very close, as she is with all her children. She often hugs and kisses me and my siblings in a manner that is intimate; any mother in the world does the same.

"That day, on the beach, we walked around with each other completely aware of the presence of photographers there.

We have nothing to hide and, with that in mind, I would like to say that I am openly gay."

The Seymour-Brant photos also set me thinking about the potential minefields in future public displays of affection (PDA) with my two growing boys.

An informal poll of my friends who are also mothers of young sons revealed that all of them were slightly creeped out by such overt displays of PDA.

"Even between husband and wife, there should be a line you don't cross when it comes to PDA, right?" mused one very civic- minded mother.

As we pondered questions like "to kiss or not to kiss once they reach puberty?", "on the lips?" and "how old is too old to bathe with Mummy?", my friends and I arrived at a stumped silence.

Back home, my four-year-old-going-on-five son, Julian, improvises our style of kisses. He puts his fist on his lips, I put my fist on my lips, and then we bump fists.

When he is 18, that will be our secret PDA - if he is still keen on kissing dowdy old Mum.

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