Birthrates in “1st world” countries are falling and who can blame us for failing to reproduce as the rewards of raising kids become ever slimmer and raising babies and young children becomes an increasing handicap in an ever more competitive world economy.

It’s happening among my friends as they approach their mid thirties. Kids are a status symbol of wall to wall childcare or stay at home yumminess, or a career breaker that no one regrets, exactly, but certainly feels the pinch. My gay friend, Laird, with four degrees and a jet setting lifestyle, has surprised himself by becoming broody, but hasn’t yet figured out the logistics. For many people, it’s still a choice between a successful career or parenting. Having it all has long gone by the wayside.

My sister, Katie is a case in point. She’s a ball breaker, a head honcho, a feisty go-getter who has grafted, flirted, commuted and stilettoed her way to the top of the tree in a top UK manufacturing company. For her efforts she is handsomely rewarded, but by god does she put in the hours.

She has a daughter, Sammie, two and a quarter, and a patient, gentle other half, Dave, who stays at home to raise her while Katie negotiates salaries, hires, fire and puts the wind up her line manager. Her job is so much a part of her identity she floundered on maternity leave; her earnings, which more than keep the family afloat, her main source of stability. Having another child, she says, would be career suicide, which is interesting coming from someone who is head of HR.

Be that as it may, my interest is more in how being an only child affects her daughter. Sammie is far from alone. This Christmas, I entertained the only children of several of my friends, and all of them garner a considerable share of their parents attention. Many of them are only children of single parents, which perhaps puts a different complexion on things, but certainly compared to my two, who very much look after each other, giving me the option to opt out perhaps more often than I ought, only kids appear to be pandered to in a way that I find a little over the top. But is any of this actually harmful? Does it make them too needy, or in fact, without having to compete for parental love, does it have the opposite effect of making them very secure?

Obviously there are too many variables involved in parenting to ever be able to draw a sweeping conclusion, and my own very non scientific observations would suggest that it can go both ways. Katie’s Sammie is happy amusing herself, and her father’s unflinching attention has made her seem very confident, although perhaps a little demanding. But then, most two year olds would come under this bracket. The older onlies I know can be a little worse at sharing, more prone to histrionics when ill, used as they are to their own things and the undivided interest of their parent(s), but by contrast they can also be very generous of spirit without having to share with siblings all of the time or put up with the diminishing returns of hand-me-downs, smaller bedrooms or earlier bedtimes; and perhaps they end up more independent too – Ava, at five has become exceptionally needy of Jonah, and won’t go anywhere without him, having been his shadow for her entire childhood.

Looking outwards, and on spurious evidence garnered from the telly and articles online, the documented effects of China’s one child policy on the national character have been noted, but the jury’s out on whether communism as an ideal can re-balance what lack of familial competition does to a child. If a generation of “little emperors” grow up insular and spoilt, market forces in a competitive economy will soon knock their corners off, and competing for the rather fewer females than there ought to be might be penance for not having to fight for their parents’ attention, and will certainly sort the wheat from the chaff – and hopefully in the future give women higher status – or at least market value – in a nation whose rapid u-turn and necessary loosening of the one child policy in an ageing population hasn’t resulted in offspring Armageddon – far from it – birthrates are slipping as in all developed and developing countries s families realise and shun the increasing burden of child rearing.

So only children are the future. Bigger families are increasingly disparaged in the West, remaining the preserve of the opposing ends of the class spectrum, and fewer and fewer of us will be able to afford the financial and time investment required to rear a brood as market conditions adapt to smaller families.

But having spent the holidays with my own sibling, I know life would be lesser without one. There is a unique bond of love and loathing that holds us together. Katie knows me the best of everyone, and yet her version of me is coloured by childhood squabbles, shared experiences and shorthand assumptions based of earlier versions of myself. There is no one who can quite get my goat quite so quickly as my sister, as familial traits are magnified into caricatures when we are forced to share the same oxygen. And yet, it really wouldn’t be Christmas without her. When all else fails, Katie is always there, chiding me about my dietary choices and congratulating me on my colour schemes. She props me up, and reminds me who I am, weighs me down and provokes emotions that are often best left in the attic of my soul. She is as much a part of me as my children, and to be without her would be to lose part of myself. Perhaps, as an only child, her daughter may feel more complete without the need to compete for her parent’s affections, but a little healthy competition never did anyone any harm either.

So I say here’s to siblings. The world would be a sadder place without them. And if Katie got knocked up again, it would make a better case for me doing so too, so we can compare, contrast, congratulate and commiserate as only sisters can.