1. We apply gender stereotypes to babies from literally the moment they're born.
A study by researchers at California State University found that when shown a picture of a crying baby, children as young as 3 were more likely to say the baby was "sad" if told it was a girl and "angry" if told it was a boy, because of the stereotypes surrounding those genders.
It was a small study, but its findings have been repeated in other contexts and at other ages. We really do seem to apply "girlish" and "boyish" stereotypes even to babies far too young to have any sort of girlish or boyish behaviours.
2. Small children don't know you are a person with a mind of your own.
If you've got a small child, you may have noticed that it spends a lot of time pulling your hair, or biting you. This isn't because it hates you and wants to cause you pain: It's because, before a certain age, it simply doesn't occur to the child that you have a mind which can feel pain.
A developmentally normal child of 5 is a highly gifted mind-reader – as are most of us. We are able to guess, with remarkable accuracy, what the person we're speaking to is thinking, what they're aware of, what they think you think they're thinking. But at the age of 3, most children can't do any of this stuff.
There's an experiment in which children are given the following scenario: Someone puts a marble in a box, and then leaves the room, and someone else moves the marble from the box into another one. The children are asked where the owner of the marble will look when they come back into the room. Up until they are about four, most children will say the second box, because they know the marble is there. They can't think themselves into the mind of someone else who has access to different information.
Earlier in life, children are even worse at this: For instance, up until between 12 and 18 months, if you point at something, they'll look at your finger, not the thing you're pointing at. And if you perform an action – say, trying to hang a loop on a hook – but fail at it, children will only work out to repeat the thing you were trying to do at about the age of 18 months. To do so would mean realising that the big creatures that give them milk and wipe their bottoms have goals and needs of their own, and that is quite a sophisticated idea.
3. Children have to learn how to lie – and for a while they're hilariously bad at it.
Sure, by the time you're a teenager you've really mastered the lying-to-your-parents thing. I'll be home by midnight; no, I haven't been smoking; what do you mean, running a major arms-smuggling and prostitution racket from your garage? But younger children simply do not have the skills.
In an experiment in which children were left in a room with a toy but told not to look at it until the experimenter returns, of course most of them did look. But when challenged, most 2- and 3-year-olds immediately confessed their terrible crime; the older they were, the more likely they were to lie about it.
What's brilliant is that they aren't necessarily very good at it. As well as being asked whether they looked, some children were asked what they thought the toy would be. Despite having just claimed not to have looked, younger children who lied would blurt out what they knew the toy was ("Barney!"). But slightly older children tried to be less obvious. One 5-year-old said: "I didn't peek at it. I touched it and it felt purple. So, I think it is Barney." By the age of 7, most are accomplished liars.
4. Babies are super racist.
No one is born racist, goes the saying. And it's true, just about. But by three months old, babies prefer to look at faces of the race with which they are most familiar. However, it showed that children brought up in a multi-ethnic environment showed no preference for one ethnicity over another. Which is hopeful news for those of us with small children in large, multi-ethnic cities.
5. You're OK to drink coffee when pregnant. And wine, in moderation.
When Emily Oster, an economist, got pregnant, she found that the advice on what to do and not do was unhelpful. As an economist, she expected discussion of evidence and risk: instead, she found unexplained commands, such as "don't eat cured meats" and "don't drink coffee". So she looked at the statistical evidence behind the claims and wrote up her findings in a book, Expecting Better: Why the Conventional Pregnancy Wisdom is Wrong – and What You Really Need to Know.
She found that women who drink coffee during pregnancy are more likely to have miscarriages. And that sounds like you shouldn't drink coffee, right? But it's more complicated than that. Looking at the evidence, Oster found that it's more likely to be the other way around: Women who are more likely to have miscarriages tend to drink more coffee. That may sound bizarre, but it makes sense. Some women suffer nausea during pregnancy, which puts them off coffee – but nausea is a sign of a healthy pregnancy. Also, older women – who tend to be at greater risk of miscarriage – tend to drink more coffee. The coffee/miscarriage link seems to be correlation, rather than causation, although one study suggested that if you drink large amounts of coffee and don't reduce your intake at all there may be some increased risk.
Similarly, the risk of moderate wine drinking ("Drink like a European adult, not like a fraternity brother," says Oster) is less than you might think.
She also found, by the way, that the injunction to avoid certain meats (because of the risk of listeria infection, which can cause miscarriage) is less useful than it might be. "My best guess was that avoiding sliced ham would lower my risk of listeria from 1 in 8,333 to 1 in 8,255," she said.
6. Playing Mozart to your baby (or your bump) will not make it brainier.
In 1993, a small study found that listening to classical music for 10 minutes raised the IQ of college students by eight or nine points. This led to a craze in which parents played their children, babies, or even foetuses classical music, in the hope of giving them a better chance in life. The US state of Georgia even started handing out CDs of Mozart to new mothers.
But it's nonsense. In 1999, the psychologist Chris Chabris carried out a meta-analysis of all the research into the so-called Mozart effect, and found that there was no such thing. The original study had been a fluke. "The results do not show any real change in IQ or reasoning ability," said Chabris. "There's a very small enhancement in learning a specific task, such as visualizing the result of folding and cutting paper, but even that is not statistically significant.
"There's nothing wrong with having young people listen to classical music, but it's not going to make them smarter."
It's not a total wash for "making noises to your bump" enthusiasts, though: There is some evidence that voices and songs that babies hear in the womb are more likely to soothe them when they're out in the world.
7. Foetuses can taste the food you eat in pregnancy.
Research suggests that babies will be more likely to enjoy different foods if their mother ate them during pregnancy – apparently because the food flavours the amniotic fluid. (Since the foetuses are constantly peeing into the amniotic fluid, this does make one wonder if babies would also enjoy drinking pee, but this experiment has not yet been done.)
Linda Geddes, the New Scientist reporter and author of Bumpology, reports on a study from 2001 in which "the infants of mothers who drank 300 millilitres of carrot juice four times a week for three weeks during the last trimester of pregnancy, or during the first two months of breastfeeding, showed a greater enjoyment of cereals prepared with carrot juice once they were weaned". Later studies have found similar results.
8. If left to their own devices, children will invent their own language.
Children are extraordinary language-learning machines. You don't really have to teach them anything – they'll pick it up from listening to your speech. (Western parents constantly feel they have to explain the language to their children. But, as Steven Pinker notes in The Language Instinct, lots of other cultures simply don't talk to children until they're capable of talking back, and they pick up their local language just fine.) But where it gets really interesting is if the adults they're around don't speak a language the children can use.
During the slave trade, groups of slaves and labourers were brought from all over the world. The different groups didn't speak each others' languages, but cobbled together a sort of crude patchwork, known as a pidgin. "Pidgins are choppy strings of words borrowed from the language of the colonisers or the plantation owners, highly variable in order and with little in the way of grammar," writes Pinker. But as the children of pidgin-speakers grew up – especially if isolated from their parents, perhaps looked after by a pidgin-speaking worker – they often gave those pidgins highly complex grammar, creating a "brand-new, richly expressive language" known as a Creole.
Another example, away from the horror of the slave trade, is in deaf communities. Sign languages such as British Sign Language and American Sign Language were not, as often thought, created by well-meaning educators, but grown naturally among communities of deaf people. And in 1979 in Nicaragua, the government created the first schools for the deaf. The teachers focused on lip-reading and speech, and it didn't work – but in the playground the children created their own system, which is now called the Lenguaje de Signos Nicaragüense. It has no relation to Spanish, and BSL and ASL have no relation to English: Pinker says that ASL has grammatical rules more reminiscent of Navajo and Bantu.
9. You aren't a product of your upbringing.
Nature or nurture? Psychologists use the terms "genes" and "environment". Further, they divide "environment" up into "shared environment" and "unique environment". Shared environment is our home upbringing, school, neighbourhood, and all the things we share with our siblings. The other half is what is confusingly called the "unique environment", but it essentially means "random other stuff" – the unquantifiable things that only happen to you. So "shared environment" includes all the stuff that you mean by "upbringing".
When it comes to things like intelligence and personality, Steven Pinker, in his book The Blank Slate, says that twin studies have shown that the effects of shared upbringing "are small (less than 10 percent of the variance), often not statistically significant, often not replicated in other studies, and often a big fat zero… [A]ll things being equal, children turn out pretty much the same way whether their mothers work or stay home, whether they are placed in daycare or not, whether they have siblings or are only children [and] whether they have two parents of the same sex or one of each."
Not that that means upbringing isn't important. It's hugely important – but in a different way. As Judith Rich Harris, author of The Nurture Assumption, points out, you may not be able to determine how intelligent or hard-working your child is, but you can easily make them miserable, or give them unhappy memories of childhood. Just don't go into parenthood thinking you can mould perfect little children. You can't.