This article analyses variation in the family background of young homeless people in a cohort of young Danes. The study is based on administrative data for individuals who were 18 years old in 2007 and their parents. Homelessness is measured by shelter use over a five-year period. Data also cover education, employment, mental illness, substance abuse problems and placement outside home in childhood for the young persons, and education, employment, civil status, mental illness and substance abuse problems for their parents. A cluster analysis identifies two groups, each comprising half of the young shelter users. In the first group, social marginalisation is transmitted between generations, as most parents have low education and mental illness or substance abuse problems, and are unemployed. In contrast, the young people in the second group come from wider socioeconomic backgrounds, with few of their parents having mental illness or substance abuse problems. These young people develop psychosocial problems and become homeless without strong predictors from their family background. Amongst the young shelter users from families with severe social problems a higher share are in the Not in Education, Employment or Training group. They also have more shelter stays, compared to young shelter users from families with fewer social problems.