When people respond negatively to an event, even one seemingly benign to others, they might talk of being “triggered” – meaning an emotional button has been pushed, and a discomforting, upsetting or even traumatic experience has been conjured from the past.

Triggering is a big conversation.

The point here is that your reaction to the event is all to do with how the world has treated you.

Less discussed is the fact that some people are more “sensitive” than others.

Unhappy or stressful moments are felt more deeply: It’s just the way they are.

Parents worry about this, sometimes hysterically. One of the kids cries or sooks more easily, more often.

Some wonder: Who did this to our child?

Others quietly lament that they’ve spawned a weakling: Some quirk in the genetic marriage. They’re half right.

A new study from Queen Mary University of London says: “Some people are more sensitive to others – and around half of these differences can be attributed to our genes.”

The researchers, developmental psychologists, compared pairs of identical and non-identical 17-year-old twins “to see how strongly they were affected by positive or negative experiences”.

The idea was to establish each participant’s “sensitivity level”.

The plan was to “tease out how much of the differences in sensitivity could be explained by either genetic or environmental factors during development”.

What was their plan?

As the researchers explain it:

• Twins who are brought up together will mostly experience the same environment
• Only identical twins share the same genes: Non-identical twins are like any other sibling
• If identical twins show no more similarity in their levels of sensitivity than non-identical twins, then genes are unlikely to play a role.

This analysis concluded that 47 per cent of the differences in sensitivity between individuals were down to genetics, leaving 53 per cent accounted for by environmental factors.

The researchers says their study is “the first to show this link conclusively in such a large study”.

Michael Pluess, Professor of Developmental Psychology at Queen Mary University of London and study lead, said: “We are all affected by what we experience – sensitivity is something we all share as a basic human trait. But we also differ in how much of an impact our experiences have on us.

“Scientists have always thought there was a genetic basis for sensitivity, but this is the first time we’ve been able to actually quantify how much of these differences in sensitivity are explained by genetic factors.”

How did the study work?

More than 2800 twins were involved in the study, split between about 1000 identical twins and 1800 non-identical twins, roughly half of whom were same sex.

The twins were asked to fill out a questionnaire, developed by Professor Pluess, “which has been widely used to test an individual’s levels of sensitivity to their environment”.

This test will be made available online later this month so anyone can assess their sensitivity.

The questionnaire is designed to “tease out different types of sensitivity – whether someone is more sensitive to negative experiences or positive experiences – as well as general sensitivity”.

Co-researcher Dr Elham Assary said: “If a child is more sensitive to negative experiences, it may be that they become more easily stressed and anxious in challenging situations.

“On the other hand, if a child has a higher sensitivity to positive experiences, it may be that they are more responsive to good parenting or benefit more from psychological interventions at school.

“What our study shows is that these different aspects of sensitivity all have a genetic basis.”

The researchers also explored if there was a shared genetic component between sensitivity and the personality traits known as the “Big Five”.

These are openness, conscientiousness, agreeableness, extraversion and neuroticism.

They found that “there was a shared genetic component between sensitivity, neuroticism and extraversion, but not with any of the other personality traits”.

Professor Pluess said the findings “could help us in how we understand and handle sensitivity, in ourselves and others”.

He said: “We know from previous research that around a third of people are at the higher end of the sensitivity spectrum. They are generally more strongly affected by their experiences.

“This can have both advantages and disadvantages.

“Because we now know that this sensitivity is as much due to biology as environment, it is important for people to accept their sensitivity as an important part of who they are and consider it as a strength, not just as a weakness.”