There are now 2.7 million households in the UK with adult children living at home.
Research shows that more than a quarter of 20 to 34 year olds still stay with their parents.
The cost for mums and dads across Fife rests at approximately £1200 a year.
Carolyn Fairbairn, Chair of the Centre for the Modern Family, said: "This research highlights the very real pressures being felt by Full Nesters as a result of the rapid emergence of the 'Never Fledged Generation'. With many parents raiding their savings or putting their retirement plans on hold to cover the cost of their adult children still living under their roof, we need to ask ourselves what the longer term implications of these trends are and what this means for the financial well-being of these parents.
"As a society, we must make sure that any interventions geared towards helping young adults take their first independent steps in life do not take for granted both the support and sacrifices of their parents. For while every Full Nester hopes that their 'Never Fledged' offspring will eventually spread their wings and fly, they might find that on their departure they are faced not only with a bare and empty nest, but also radically diminished nest egg with which to secure their financial future."