The data gathered from the COVID Symptom Tracker app suggests that genetics make some people more susceptible to coronavirus infection than others. The researchers also asked thousands of twins in the UK to use the app.

They used the data they gathered to try and establish whether the genetic makeup was related to the symptoms experienced by those participants expected to have COVID-19.

Their results reveal that 50% of the differences between people's symptoms of COVID-19 are caused by genetics. These symptoms include delirium, fever, fatigue, shortness of breath, diarrhea, and loss of taste and smell.

But other symptoms like having a hoarse voice, cough, chest pain, and abdominal pain were thought to be caused by environmental factors and not because of genes.

Twin studies: identical and non-identical

As part of the TwinsUK, researchers are allowed to research on identical and non-identical twins to understand to what extent genes (nature) and environment (nurture) affect the health and disease.

Around 5,000 twins and their families in the UK had been recruited from the TwinsUK project to test the app.

Professor Tim Spector, a genetic epidemiology at King's College in London and one of the leading developers of the app, said that the main goal of the research was to look at similarities in symptoms or non-symptoms between identical twins who share 100% of their genes, and those non-identical twins who only share 50% of their genes.

"If there is a genetic factor in expressing the symptoms then we'd see a greater similarity in the identical than the non-identical and that is basically what we showed," Spector said.

He added that the disease presents itself differently in the population among different people and it is not mainly because of your environment; it has more to do with what is innate about you. The likelihood of getting it at all or severely is under some genetic control.

The researchers hoped that their findings will help future studies on how to go about developing treatments for the deadly virus, as well as identify high-risk groups. The 'COVID Symptom Tracker' app is available for iOS and Android that lets UK citizens self-report their health status daily.

COVID Symptom Tracker

The tracker provides real-time locations of COVID-19 symptoms as they occur. The researchers from King's College London made this app in collaboration with the Guy's and St. Thomas' hospitals and health data science company ZOE.

It became the third most popular app in Apple's UK store just 48 hours after its launch in late March. The developers of the app confirmed to MailOnline that it was downloaded at least 50,000 times an hour. As of today, about 2 million people in the UK have already downloaded the app, which is helping scientists to get data on the progression of the virus.

However, almost 75% of the users have stopped using the month earlier this month. Professor Spector urged people to keep using the app to help the NHS. Doing that will help them know how people are feeling even if they do not have the symptoms, and they will be able to track the disease in real-time and allocate resources where they are needed most. The individual contribution will play a big role in the UK's collective effort to beat the virus in their country.