“WILL you please answer me!”

I must have uttered these words millions of time while raising my children - the majority of them during their teenage years.

I wasn’t alone. My friends were also regularly ignored by their teens and we would sit and moan about it over endless cups of tea.

Like other parents I thought it was all due to raging hormones but a new study suggests there may be a scientific reason. Research found that teenagers' brains start tuning out their mothers' voices around the age of 13.

This is because they no longer find it 'uniquely rewarding', researchers said, and instead tune into other people's voices more.

It makes sense. There comes a time, not long after starting secondary school, when kids begin to attach far more importance to what their friends and others, have to say than their parents.

Their peer group becomes more important to them whereas parents suddenly become surplus to requirements.

At the time it made me sad - to think that the little kids I had raised, who had looked out for me and raced to meet me outside their primary school, keen to tell me their news, now blanked me when I asked them something.

As teens they would come in from school and I would attempt to get eye contact and ask about their day, while they carried on walking past me and up the stairs to their rooms. Even when they were in the same room, sitting having a meal or watching TV, they didn’t fully engage when I spoke to them.

The only time I could pin them down and get their attention - I won’t say undivided because that never really happened - was in the car, when they were trapped and had no escape, but even then they used headphones and I had to resort to shouting.

The study by the Stanford School of Medicine used functional MRI brain scans to give the first detailed neurobiological explanation for how teenagers begin to separate from their parents.

It suggests that when your teenagers don't seem to hear you, it's not simply that they don't want to clean their room or finish their homework - their brains aren't registering your voice the way they did in pre-teenage years. The brain's shift toward new voices is an aspect of healthy maturation, the researchers said.

I used to blame my daughters’ behaviour on the stress of being a teen, on boys, spots, exams, you name it. Had I known it was rooted deep in the brain I might have cut them some slack. It always amazed me how my relentless questioning didn’t wear them down - they probably didn’t even hear it.

I also believe that teens are unable to judge their parents’ emotions. I know with my daughters, whether they were being yelled at or simply ticked off, they looked at me with the same disinterested ‘can I go now?’ expression. It used to drive me mad. I’m sure I did the same as a teenager when my dad flew off the handle, and he became even more furious as a result.

Now that one mystery of the teenage mind has been cleared up, perhaps academics could turn their attention to adults’ and why they filter out those closest to them.

My daughters have long ago left home, but I still spend half my life saying: “Will you please answer me?” as my husband’s brain also doesn’t seem to be wired up to accept my voice.

“What did I just say?” I will ask him to his deliberately vacuous face, knowing that he won’t have a clue. A 60-year-old going on 15.