Since 1996, despite a consistent number of people in the 20-34 age group, the number of those living with their parents jumped to 3.3 million in 2013, the Office of National Statistics said.
ONS said a higher percentage of young adult men live with their parents compared to young adult women.
About 33 percent of 20-34-year-old men live with their parents. For women, about 20 percent of young adults live with their folks.
Separately, ONS said the 2011 Census indicated that 58,000 people in the country identify themselves as gypsy or Irish Traveler, which is 0.1 percent of the general population of England and Wales.
The demographic group has a higher percentage of youth under 20 with 39 percent of the group listed as under 20, while 24 percent of the general population is listed as under 20.
Those identified as gypsies and Irish Travelers as a group included 20 percent unemployed, compared to 7 percent for the general population, ONS said.