The question oft posed by childless friends is what is the hardest aspect of early parenting. In response, it is too easy to trip off an expected list of sleepless nights, the early days when you don’t have time to brush your teeth, marching around in the rain with a wailing baby in a pram, seeing poo ooze out of a nappy in the small hours of the morning, etc. But the recurrence of this question started me thinking.

It seems we approach parenthood with a sense of trepidation. This, from people who work long hours in pressurised jobs, often in meetings with important people. You would think they are used to ‘hard’. No, they suspect parenthood to be hard in a different way.

My interest in the question is not to say that I, to date, have found our babies a bed of roses. There have been plenty of times in the last seven months that I have felt so tired I could burst into tears – a point of fatigue I reached only twice before having children, and both times self-induced by staying up all night at a ball. There have also been moments when all I could do was to pass the baby into someone else’s arms, for whatever I was doing did not seem to be working. And, I have even muttered almost angrily under my breath when catching a whiff of something unpleasant through the night air. But these are just physical tests, rather like running a long race, which if you carry on plodding through mostly at a steady pace, you will do alright. These aspects are manageable, however momentarily frustrating.

This, however, is where the race analogy stops, because every other race – career, half-marathon, relationship – you are allowed to quit, and you know it, even if you don’t. Not this one. Once the babies are there, they are yours and yours to manage come what may. Recognising this is incredibly exciting, awe-inspring even, but it can also feel a little overwhelming, or, let’s say, hard.

I also wonder if our generation is making parenting more complicated than it need be. Both men and women work longer hours than ever before. Most of us, at least if we want to get on in our careers, arrange our working lives in such a way that makes a baby completely incompatible or at least very expensive (and stressful) in childcare. We tend not to live in the bosom of our extended families, those lovely (though sometimes oppressive) networks of ready help. The cities which offer us the best salaries offer hand in hand the highest rents, so that our homes are either too cramped with a child or spacious and too far away from easy public transport and our friends to make us happy. (Luckily for me, just before our babies were born we moved to a city where rents are not sky high.)

At the same time, we have huge expectations for our experience of having a family. We want our babies to be born in a certain ambience with the right music on in the background, whilst following a breathing pattern learned in a prenatal yoga class. Once there, the baby must only wear organic cotton, and every tiny chirrup will send us scouring the pages of our multiple baby books. God forbid, the precious child does not roll over before it is six months old because then we have another three appointments a week at a baby physiotherapist, which is hard to fit in around baby massage, sing time and all that book reading. And, we still want to go on exotic holidays of course, but what to do with the baby on the long flight.

I would love to ask my grandmothers (both well-educated women with interesting jobs) whether they thought having small children would be hard. I don’t know what their answers would be, but I am sure they would say that rising to the challenge was one of the very best things they ever did.

“Isn’t it strange that they are so different?” people often say to me of our twins, in response to the way they look, behave with strangers, move, eat, babble or laugh. But I do not find it strange at all. Why should twins be alike? I suppose there are some genetic reasons which we do not yet understand for why identical twins may be more likely to be alike than other siblings, but for non-identical boy and girl (or any non-identical) twins, who genetically are no more alike than siblings, this seems a significant assumption.

It is this assumption and its possible consequences I find interesting. One explanation is that when you mention twins most people think of the identical type, not remembering that this cannot be possible with a boy and a girl – an unpractised mental leap. That aside, our experience tells that most people expect any twins to be alike and, what is more, are surprised when they are not.

Do we expect siblings to be alike? When they are older perhaps and have the grooming of shared experience, but even then we do not go out of our way to express incredulity when they are not. So why then twins, and particularly as babies?

I wonder whether this will continue throughout their childhoods and what impact this may have. The natural rebel would suggest that you are tempted to try much harder to be different when everyone thinks you should be alike. So, I suppose the least I can do is never assume that they will be similar in anything, and always offer to make two birthday cakes each year, whatever their favourite may be.