A quarter of these couples moved back to the family home to save for a house deposit, while 12% returned after graduating university.
A further 12% could no longer afford their rent, according to the study by Churchill Home Insurance.
Less than a third of parents charge their child to stay at home, the survey found. For those who do have to pay, the average monthly rent is £115.60, more than eight times less than the average monthly rent in the UK, which is £928.
A spokesperson for Churchill home insurance, said: “Moving back in to the family home is becoming ever more popular and is often the only choice for young adults who are trying to save up for a house deposit of their own. Whilst it is surprising that so many have opted to move back in with their parents with their partner in tow, this does allow couples to save more whilst still living together.”
According to the research, most parents welcome their children home with open arms, with 28% pleased they could spend more time with their child and 26% pleased to give them the opportunity to save for their own home.
However, not all are pleased to have their kids return to the nest, with a third of parents (34%) reporting a negative outcome following their child and partner moving in.
The biggest cause of disputes were their offspring and their partner failing to help with housework, with one in seven parents feeling frustrated they did not help with jobs and chores and 11% feeling as though they treated the house like a hotel.