Some celebs just can't help but pick partners who look like their exes. So who said opposites attract, asks Ed Power
It is one of the mysteries of our age. Wealthy, famous and (usually) beautiful – in theory, celebrities should have their pick of romantic partners. So why do so many of them date virtual lookalikes?
Consider Leonardo DiCaprio, serial wooer of blondes with legs stretching into next week.
He's like the guy who refuses to contemplate the existence of any flavour of ice cream other than vanilla. In the same category belongs Kate Moss, long-time devotee of the sort of jaded rebel who sleeps in their leather jacket and polishes off a bottle of whiskey with their cornflakes.
And what of Madonna, and her seemingly never-ending parade of chiselled toyboys? Her most recent beau was 28-year-old Brazilian dancer Jesus Luz. She was also, of course, married for eight years to square-jawed Guy Ritchie.
Her 1990s boyfriend was personal trainer Carlos Leon, a body-beautiful type with pecs that could crush a walnut.
You could spend all day listing celebrities who believe in sticking with what they know. Boris Becker's wife Sharlely Kerssenberg is often described as a doppelganger of ex-wife Barbara Feltus – and bears a striking resemblance to five other of his exes: Angela Ermakova, Sabrina Setlur, Patrice Farameh and Caroline Rocher.
The temptation is to dismiss all of the above as a quirk of Hollywood. Until, that is, you consider the dating habits of Irish celebs.
Other than feed our suspicion that celebrities are horribly shallow, what does any of this prove?
In fact, the evidence is that celebs do not consciously set out to woo a specific 'type'. None of us do. It is simply how we are wired. Our romantic preferences are hardwired at a genetic level. It's a cliché but celebs, like the restof us, are at the mercy of their hormones.
The laws of attraction have a lot to do with the science of beauty, and several generalisations may be made. We all know instinctively that a person's life will likely be easier if they are born good-looking. And the data backs this up.
So how does beauty work? The answer, studies inform us, boils down to symmetry.
Researchers at the University of Nebraska tell us that symmetry between the two halves of the face is the quality we most desire.
The figures are stunningly precise. They involve a 'golden ratio' – the length of the face relative to its width. The ideal, according to Dr Kendra Schmid of Nebraska University, is 1.6.
This sounds like hooey until you consider the results. Rated out of 10, the highest score measured by Schmid and her team was achieved by Brad Pitt, who came in at 9.3.
His partner Angelina Jolie achieved 7.67, losing points for her big lips (maths are no match for the Angie trout pout).
To put it in context, the average person would score between four and six. Brad Pitt isn't just a little bit more beautiful – he's a lot more beautiful.
So why don't we all fancy the same type of person?
As is often the case with science, the answer is horrendously complex.
The simplified version is that the subliminal search for genetic perfection can influence us in the strangest ways, not all of which come down to whether someone is conventionally good-looking or not.
So, one reason Johnny Depp has proved irresistible to Kate Moss, Winona Ryder and the mother of his two children, Vanessa Paradis, it is suggested, is that, with his expressive eyes and sensitive mouth, he comes across as less of a Neanderthal than the average movie star.
The evidence is that, even if some women are, in the short-term, drawn to 'macho' guys – because they will pass on strong genes – for lengthier pairings, they prefer men with feminine qualities as this indicates they are gentler and make for better life partners.
Science can provide an insight into Leonard DiCaprio's penchant for lithe blondes, too. Research has demonstrated that long legs are seen as desirable in women. The theory is that they are an indicator of fitness.
Some studies have theorised that taller women have wider pelvises, which is useful in child birth. Plus, the longer your legs relative to the rest of your body, the lower the risk of cancer and heart disease.
At some subterranean level, a voice in Leo's head is whispering, 'long legs good, short legs bad'.
There is also that category of celebrities who bear an uncanny resemblance to one another.
Many have commented on the similarity between Brad Pitt and Angelina Jolie. Head on, they could be siblings, sharing the same strong jaw, lean nose and wide face.
"Like attracts like," says dating expert Sharon Kenny.
"When people say, 'Oh I want someone completely different', you get them to do their profile and it turns out they are looking for a person like them.
"One of the most intriguing ideas is that couples grow to look similar," adds Dr Stuart Farrimond, editor of 'Guru Magazine'.
One 20-year-old piece of research concluded that as married couples grew old, their faces became increasingly alike.
The researchers suggested that because couples often mimic each other's expressions, their facial muscles gradually strengthened in the same way – ultimately resulting in a similar-shaped face.
In other words, if you think Brad and Angie resemble blood relatives today, imagine what they'll look like 20 years from now.