Image: Nigel Mykura Image: Nigel Mykura

One million more young people aged 21-34 are likely to be living at home with their parents by 2025 because they cannot afford hefty mortgage deposits.

The study, by Aviva, estimates around 3.5 million people in that age bracket will be living with their parents, up from 2.5 million now.

Aviva said the number of young people living with their parents grew by a third (32%), or 700,000 between 2005 and 2015.

The insurance provider pointed to rising house prices, which have grown by 52% in the UK during that 10 year period to an average £279,000, as the main reason for the expected increase.

Research released earlier in May claimed that the 'bank of mum and dad' will help fund a quarter of all mortgage deposits in the UK, contributing an average £17,500.

Aviva's Lindsey Rix said: “Multigenerational living is often seen as a necessity rather than a choice, particularly when adults are forced to move back in with family to help save for long-term goals like buying their own house.

“But rather than being an inconvenience, our report shows it is often a positive experience, with shared living costs reducing financial strain and the added benefit of constant company.”

Interestingly, saving more a mortgage deposit wasn't the most common reason for staying at their parents, or moving back. Instead, 71% said they would in order to care for an unwell relative.

Two-thirds (66%) of those already living with their parents said it was a positive experience, compared with just 42% of those not currently living at home.