Lack of understanding develops between people of widely different age groups, particularly between children (usually from the age of adolescence) and parents, grandparents etc. This lack of understanding may lead to the rejection of the children by the parents or, at a later stage when the parents are in need, the rejection of the parents by the children. It may lead to: family breakdown; juvenile delinquency; hooliganism and assault on older people by youth gangs; destruction of property; student unrest. Equally it may lead, because of fear and prejudice, to rejection of new ideas by older people and resistance to change. On the other hand, the abilities of youth may be overvalued in comparison with those of older people, leading to early retirement, unemployment and neglect of middle-aged and older persons.
The generational conflict, or conflict between age-groups, is largely due to the educational revolution, which gives the adolescents of today intellectual tools that their parents very often did not have. It is also due to the "knowledge revolution", making the knowledge of the parent generation more irrelevant. This is not only because there has been a quantitative accumulation since they formed their images of the world, but also because of the qualitative changes of paradigms that seem to take place with increasing speed today. There is little reason to believe that these trends will not continue, and the net result is increasing irrelevance, dissimilarity, and heterogeneity, between generations.