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The phenomenon is not confined to Japanese society; analogous or similar phenomena can also be found in other cultures. For example, in Italy, some young adults (especially singles) still rely on their parents. They were joked about by the former Italian Minister of Economy and Finance Tommaso Padoa-Schioppa, who called them bamboccioni (literally, big [i.e., grown-up] babies). Padoa-Schioppa's "boasting" was considered extremely offensive by some people, and newspapers pointed out that he knew little about the situation of a considerable part of the 20–30 years old Italian population, who do not earn enough money to afford leaving their parents’ house. In Germany they are known as Nesthocker (German for an altricial bird), who are still living at Hotel Mama ("Hotel Mama" is an ironic term for the parental home, since the household chores and the cooking of the meals is done by the mother alone), an expression also commonly used in Flanders. In English internet parlance, the expression "basement dweller" is sometimes used, referring to someone who lives in his or her parents' basement.
A different concept of parasite single is found in Brazil, where some individuals are said to rely on Paitrocínio (a pun with the words Pai or Pais, meaning father and parents respectively, and Patrocínio, meaning sponsorship). This word is used not for the ones living in their parents home, but actually for the ones who did leave home, albeit still relying solely, or majorly, on parents financial support. The reasons for leaving home before achieving financial independence vary, but mostly it is due to college or to start a career with small or uncertain initial incomes, such as in arts and sports.
The expression parasaito shinguru was first used by Professor Masahiro Yamada of Tokyo Gakugei University in his bestselling book The Age of Parasite Singles (パラサイトシングルの時代, parasaito shinguru no jidai), published in October 1999. The catchy phrase quickly found its way into the media and is now a well-known expression in Japan. Professor Yamada subsequently coined the related term parasite couple to refer to married children living with the parents of one partner. However, this situation occurs less frequently and the term parasite couples is less well known. This is a traditional Japanese living arrangement, though its prevalence has decreased in recent years.
While some adult children help with the household chores or pay a share of the rent, the vast majority do not. According to some statistics,[who?] about 85% of the children do not help with shared living expenses, but instead receive free housekeeping, laundry services, and meals from their parents. On top of that, about 50% of the children receive additional financial assistance from their parents.
This situation allows the children to live in considerable comfort, and while many save money, others spend all their income on luxury items, traveling, and other non-essential expenses. Many children wish to live with their parents until they marry.
The parents, for their part, often enjoy living with their children. Many parents want to protect their children and offer them the best possible start in life. Parents also enjoy the company and the social interaction and try to maintain the relationship. The additional expenses for the parents due to the additional household member are usually small, as the fixed costs such as rent must be paid regardless, and the additional cost for food and other consumables is sometimes negligible. Many parents also see this as an investment in their future, as the children will be more obliged to take care of their parents in their old age (in Japan, it is traditional that children nurse their elderly and disabled parents. In some countries in South America, this is one of the reasons why certain families grow numerous).
The housing costs in Japan are notoriously high, especially in or near large cities. A parasite single who chose to live independently would on average lose 2/3 of his or her disposable income. Furthermore, they would also have to do the cleaning and cooking for themselves. Finally, establishing a household has a large up front cost for durable items as for example a refrigerator, furniture, washing machine, and other items. The security deposit, traditional monetary gift for the landlord ("key money"), and the housing agent fee can also easily reach six months' rent; this is non-refundable and must be paid in advance. In summary, becoming independent involves large expenses, work, and a significant drop in living standard. Furthermore, as the vast majority of the Japanese population is concentrated in cities, all the employment and entertainment options desired are within reach from the parental home.
The economic advantages are enjoyed by all types of parasite singles, although there are different subgroups within the group of parasite singles. Career oriented young salarymen and office ladies could afford to live on their own, but prefer the additional financial benefits, and perhaps the company and security, of living at their parents' homes. Other adult children have difficulty finding steady employment in the current difficult economic situation. Often, they can only find part-time and low-paid jobs, turning into underemployed so-called freeters who cannot afford to live independently, disregarding if they would like to, or not. Finally, some adult children just do not want to face the competition of the outside world at all, and do not seek work at all, and in extreme situations, they do not even want to leave their parents' house. These children are referred to as hikikomori (people who withdraw from society, literally to "withdraw into seclusion").
Genda Yuji, associate Professor of the Institute of Social Science (University of Tokyo), widened the perspective from the rise of so-called "parasite singles" through proposing a socioeconomic driven view, strongly connected to the collapse of bubble economy and the inability of the country's employment system to react after the crisis:
One possible side effect of the parasite single phenomenon is the increase of the average age of the first marriage (though this is also attributable to other factors like career prospects and education). While in 1970 women married on average at age 24 and men at age 27, this has increased to 27.4 years for women and 29 years for men in 2002. This has also resulted in women having children later in life, and fewer children overall due to the decline in fertility after age 30. Subsequently, while in 1983 there were on average 1.8 children born to every woman over her lifetime, this has decreased to 1.22 children per woman in 2008.
Parasite singles are often blamed for a large number of problems in Japan, ranging from a decline in the birth rate over the economic recession to the increase in crime.
Some social scientists have attributed the rise in parasite singles to the Japanese preference for community, and that the increased rate has more to do with people not being in long-term relationships, choosing instead to concentrate on their work and the infamously long hours of a traditional Japanese workplace.
See also 
- Boomerang Generation
- Sub-replacement fertility
- Working women in Japan
- Aguilera Alfred, Nelson; Julio Fernández. Pobreza y tamaño de la familia: economías de tamaño y escalas de equivalencia demográficas para el Paraguay.
- Genda Yuji, A Nagging Sense of Job Insecurity, LTCB International Library Trust, translated by Jean Connell Hoff, 2005. Preface to the English edition, page xi.
- Genda, Chapter 2: The Parasite Single Explanation, page 43.
- CIA World Factbook: Japan
- In the UK: Adult kids 'fail to leave home'
- Unable or Unwilling to Leave the Nest? - Discussion paper by Mariko Tran in the electronic journal of contemporary japanese studies
- Parasites in Prêt-à-Porter