Science has now confirmed what you’ve suspected all along – your parents did have a favourite child.

In front of me I have two so-called “baby books”, both given to me as presents, in which I was supposed to chronicle the infant achievements of my sons, George and Johnny. George’s has been meticulously filled in: everything from the names of the midwives who delivered him, to the order in which his teeth came through, his first illness (conjunctivitis) and an account of his first Christmas so overwrought with emotion that it makes the Nativity itself seem like the warm-up act.

And Johnny’s baby book? Empty. Not a thing. Not even a record of his birth weight, or his middle names — which, I must admit, I am struggling to remember. That’s not all. On my computer, there are more than 2,000 photographs of George’s first few years — and 300 of Johnny’s.

So do I love Johnny less? Certainly not! The very idea of it. Yet if this isn’t favouritism — the urgent desire to document for posterity every twitch, dribble and grunt of one child, while blithely consigning the other to obscurity — what is?

Jeffrey Kluger, no doubt, would say I am in denial. The American science writer has just published a book in which he argues that, whether we admit it or not, parental favouritism is hard-wired into the human psyche. “It is my belief that 95 per cent of the parents in the world have a favourite child, and the other five per cent are lying,” he declares in The Sibling Effect: What the Bonds Among Brothers and Sisters Reveal About Us.

That particular figure may be guesswork, but there is plenty of evidence that would seem to back him up. Kluger cites a Californian study of 384 families, who were visited three times a year and videotaped as they “worked through conflicts”. The study found that 65 per cent of mothers and 70 per cent of fathers exhibited a preference for one child. And those numbers are almost certainly under-representative, since people behave less naturally when they are being watched.

Every couple of years, in fact, a new report comes out purporting to lift the lid on parental favouritism. Most often – though as we shall see, by no means always – older siblings seem to come out on top.

In 2009 two British professors, David Lawson and Ruth Mace, published a study of 14,000 families in the Bristol area. They found that each successive sibling received “markedly” less care and attention from their parents than their predecessors. Older siblings were even fed better, as a result of which they were likely to be up to 3cm taller than their younger siblings. They also had higher IQs, probably because they had the benefit of their parents’ undivided attention for the first part of their lives.

Anthropologists and evolutionary psychologists argue that there is a sound Darwinian logic to this. A firstborn automatically absorbs a huge amount of parental time and energy; and once you’ve invested that much in one child, you might as well keep going – if only to protect the investment.

I don’t like to think of myself as a survival-of-the-fittest type parent but, once again, the evidence is against me. I breastfed George for longer – basically, until he batted away the withered dug with a look of disgust – and weaned him like a king. Nothing passed his infant lips but fresh, organic meat and vegetables, hand-puréed by moonlight. He wasn’t allowed any sugar until he turned one, and my husband used to bake him bread made from spelt flour and aromatic spices, rather than pollute his pristine body with processed flour. By the time Johnny came along, needless to say, standards had slipped.

He was simply handed a supermarket sachet of baby mush and left to suck out the contents unaided. In Darwinian terms, it would appear, my mothering style is about as evolved as a gerbil’s. Johnny should count himself lucky I haven’t absent-mindedly eaten him.

Which boy will turn out cleverer remains to be seen; but it’s certainly true that I have always monitored and fussed over George’s developmental progress far more than I do Johnny’s. Somehow, it seems to matter more – perhaps because the oldest one is always the test case. I have no idea what I’m doing as a parent, or whether it will turn out all right. It’s anxiety, really, but it could be mistaken for favouritism.

As the oldest of two children myself, I can testify that being fussed over doesn’t necessarily feel like preferential treatment. Quite the reverse, in fact. My sister got away with far more mischief than me, simply because my parents were much less anxious about enforcing the rules.

Once, for example, a boyfriend hitchhiked all the way from Newcastle to London to visit me. I must have been about 20 at the time, and not easily mistaken for a virgin. But rules is rules, and boyfriends weren’t allowed to stay in the house – so my mum made him sleep in a tent in the back garden.

A few months later, I walked into my 16-year-old sister’s room and found an enormous pair of hairy feet sticking out from the end of her bed. From then on, despite my indignant protests, her boyfriend became a regular house guest – and not a guy-rope in sight.

As my mother herself admits, “I was harder on you because I was always worried about whether I was doing the right thing. You’re much madder with a first child. With a second one, you don’t have time to be so neurotic.” Indeed, depending on how you frame it, the benign neglect of younger siblings can itself be seen as a form of favouritism. Just last month, a survey of 1,803 British parents with two children claimed to show that younger siblings were given preferential treatment 59 per cent of the time. Parents were more likely to side with a younger child in an argument, lavish them with affection and – see? See? – let them have their own way.

The truth is that favouritism is an awfully blunt word for such a complicated subject. How we treat our children is affected by any number of shifting, interlacing factors: birth order, gender, changes in circumstances, our own childhood experiences.

Then, too, some characters just hit it off better than others. My friend Anna, the third of four sisters, says it has always been obvious which one her mother loves best: the second-born, Maggie. “The thing is, Maggie’s my favourite too,” Anna told me.

“She’s incredibly funny, inventive, rude and naughty. More than anything, my mum loves people who can make her laugh – and Maggie makes her cry with laughter.” Maggie also happens to be unusually beautiful and accomplished. “My mum never normally pays anyone a compliment, unless it’s something backhanded like ‘You don’t sweat much for a fat girl’. But with Maggie she’ll say really egregious things, like, ‘You look like Grace Kelly’. My other sisters and I tease her about it, but she still doesn’t seem to realise what she’s doing.” Now married with a baby of her own, Anna is only just starting to appreciate how much Maggie’s supremacy has shaped her own personality.

“I’m sure it explains why I care desperately whether people laugh at my jokes. I’m never going to be as glamorous as Maggie, so being funny is the only way I can compete.” It is a testament to the essential niceness of both sisters that they have managed to remain close through all this.

Not all siblings are so lucky. Terri Apter, a psychology professor at Cambridge University and author of several books on family dynamics, says the scars left by parental favouritism often run deeper than anyone realises. Buried resentments may suddenly flare up when elderly parents need looking after, or die and leave a controversial will. “I have seen grown siblings quarrelling at funerals over who was Mum’s favourite, who gave her more happiness,” Apter tells me.

The psychological fallout is unpredictable: favoured children may be left brimming with confidence, or they may suffer from terrible guilt, deliberately sabotaging their own careers or relationships because they don’t feel they deserve to be happy. Unfavoured children, meanwhile, may grow up feeling unworthy of love – or they may become adept at finding it outside the family.

It’s at this point, I must admit, that I start to feel a bit impatient with the headshrinkers. A science that can absorb so many contradictory variables hardly seems like science at all. And if, as the experts all seem to agree, favouritism is so common as to be almost universal, doesn’t that make it just – well, normal?

Undoubtedly there are families where favouritism is blatant and sustained enough to be seriously destructive. But in most cases, surely, it does not merit such pathologising.

When I solicited confessions of favouritism from my fellow parents, I had no luck at all. Lots of people admitted to treating their children differently at different times, according to their needs (and how annoying they’re being). But not one felt this reflected any fundamental preference. It is simply part of the warp and weft of family life.

“I think most of us have short-term favourites, depending on who’s going through a ‘phase’,” says Suzanne, a mother of four. “You can feel immense affection for one child on a Tuesday who then drives you to distraction on Wednesday. But the underlying love is just as intense for all of them. I think long-term favouritism is bookselling nonsense in the majority of cases.” In an anonymous online survey for the website Mumsnet, 16 per cent of mothers admitted to having a favourite child. That’s quite a lot – it’s a big deal to admit to such parental malpractice, if only to yourself – but it hardly amounts to the psychological pandemic of Kluger’s imaginings.

On the other hand, things do tend to look different from a child’s perspective. Even in the happiest families, siblings instinctively compete for their parents’ love. Scrupulous emotional accountants, they are constantly totting up incidents of perceived unfairness. So it makes sense for parents, too, to keep a watchful eye on their own behaviour.

Despite my failures as an archivist, I truly believe that Johnny feels – and is – every bit as loved as his brother. For now. In February I am having a third baby. Everyone knows that in three-child families, it’s the middle one who gets squeezed out. And to make matters worse, the new baby is a much-longed-for girl. Could she prove to be Johnny’s final nemesis?

Second and subsequent pregnancies tend to come laced with this kind of apprehension. Will I love this child as much as the last one? Too much? What will it do to the delicate equilibrium of our family?

Yehudi Gordon – the celebrity obstetrician, birthing guru and founder of the parenting organisation Babies Know – believes that, even in the womb, babies can sense how wanted they are. “If, for example, the mum has a preference for a boy or a girl,” he told me, “that information will be picked up by the child before birth. Babies might not understand language, but they understand feeling.” The scientific explanation he offers for this seems a bit vague – something about molecules crossing the placenta – but I’m not one to quarrel with an obstetrical legend.

What, I ask him, can a pregnant mother do to mitigate the effects of her own ambivalence? “It’s essential to be honest with your kids,” he says, “because if you’re not, they’ll know anyway.” If you’re disappointed by the sex of your child, he suggests, talk to them about it – both in and ex utero.

“Tune into the baby and say, ‘I really was hoping you’d be a girl, and that’s been difficult for me. But I’ve got a lot of people supporting me and I want you to know that I’m coming through it and working hard to overcome those feelings’.” Myself, I’m not so sure. Though a pre-verbal child (or, let’s face it, a post-verbal one) might not understand the exact meaning of such a statement, there are some things that are better left unsaid.

Voicing a feeling doesn’t necessarily exorcise it. In fact, it may make it harder to escape – both for you and your children. Apter, too, believes that favouritism is one form of love that should not speak its name. “Don’t admit it,” she says. “Even if you think you have a favourite, the likelihood is that feeling is transient. But if you speak it, if you tell either child, it will become fixed in their minds forever.

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Source: Telegraph.co.uk – http://goo.gl/m16uj