Why do people stutter? What we know about the causes

What is stuttering?

Stuttering is a disruption in the rhythm of speech. You know exactly what you want to say, but the word stalls on the way out. It might be a sound that repeats, a sound that gets stretched out, or a block where nothing comes at all.

What other people hear is only part of it. The rest is everything you do to avoid stuttering: the words you swap and the calls you don't answer. You can read more about that side in our guide to stuttering in adults.

Why do people stutter? The short answer

Stuttering almost always begins in childhood, typically in the years when a child is learning to speak in full sentences. About five per cent of all children stutter for a period, and for roughly four in five of them it passes. Just under one in a hundred adults stutters, and about four in five of them are men.

Researchers don't have the whole explanation. But two things keep coming up.

The brain handles speech slightly differently

Speaking is one of the most complicated things the body does. Breathing, voice, tongue and lips have to work together in a split second. There is a lot to suggest that in people who stutter, the brain handles that timing slightly differently. The exact cause of stuttering isn't known, but much points to the brain and to heredity. It doesn't sit in your willpower or your character.

Stuttering runs in families

Stuttering often runs in families. If you stutter, there's a good chance that a parent, an uncle or a grandparent did too. Heredity isn't the whole explanation, and it isn't certain that your children will stutter because you do. But it tells you something important: you were born with the predisposition. You didn't create it yourself.

Three myths about the cause of stuttering

Most people who stutter have heard at least one of them. Often from people who meant well.

Myth 1: It's nerves

Nervousness can make stuttering worse, but it isn't the cause. Many people who stutter are calm people, and many nervous people don't stutter. If anything it goes the other way: when you've stuttered for many years, you become nervous about speaking. The nervousness is a result of the stuttering.

Myth 2: It's about intelligence

There is no link between stuttering and intelligence. You know what you want to say. It's the route from thought to sound that causes the trouble. Even so, many people who stutter are seen as unsure or slow, and that's one of the reasons stuttering can hurt so much.

Myth 3: It's the parents' fault

Stuttering isn't caused by upbringing. It doesn't come from a strict father, a busy mother or a divorce. If you're the parent of a child who stutters, you haven't done anything wrong.

Why do people stutter more in some situations?

If the cause lies in the brain, why don't you stutter all the time? Because the situation affects how much the stutter comes out.

Most people stutter more:

• under time pressure, for example when someone is waiting for an answer
• on the phone, where the other person can't see that you're in the middle of saying something
• when they have to say their own name, which can't be swapped for another word
• when they're talking to someone they want to make a good impression on

And most people stutter less, or not at all, when they sing, speak in unison with others or talk to themselves. That shows there's nothing wrong with your mouth or your voice. Your speech works. It's the interplay between speech, body and expectation that locks up.

It also explains the good days and the bad days. Tiredness, pressure and the expectation of getting stuck turn the stutter up. They don't create it.

Why stuttering stays with adults

You were born with the predisposition to stutter. But much of what weighs on adults is something you've learned along the way. The first time a word got stuck in class and someone laughed, you learned that the word was dangerous. Next time you went round it.

Avoidance works in the moment, and that's why it becomes a habit. But every time you go round a word or a situation, the fear grows a little. Your body tenses before you've said anything at all, and the tension makes it harder to get the word out. That's how stuttering and fear keep each other going.

That is actually the good news. You can't change your genes, but you can work on your breathing, the tension and the avoidance. That's where there's something to be gained.

What can you do once you know why you stutter?

There is no cure for stuttering. But there's a big difference between stuttering and letting stuttering decide what you say and do. Many adults gain control of their speech and say what they want, when they want.

Here are four places to start:

• Say it out loud. Tell one person that you stutter. It takes away much of the pressure when you no longer have to hide it.
• Notice what you avoid. That's often where stuttering takes up the most room.
• Get an overview of your options. We've gathered them in the article on stuttering treatment for adults.
• Talk to someone who stutters themselves. Many adults never have.

On a McGuire course you work on exactly the things you can do something about: a new way of breathing, techniques for the words that get stuck, and the fear of speaking. All the instructors stutter themselves and have been through the course. You can see the upcoming courses in Aarhus, Malmö and Oslo on the front page.

If you suddenly start stuttering as an adult

All of this is about stuttering that began in childhood. If you've never stuttered before and suddenly start as an adult, the explanation is a different one, and you should talk to your doctor first. Read more in the article on sudden stuttering in adults.

Frequently asked questions