When asked where home is, Luke's answer is simple yet heartbreaking: ''nowhere''.The 19-year-old spends most nights couch-surfing at mates' places. On the nights when he is unable to find somewhere he is left on the streets.Luke and his 16-year-old girlfriend, Alicia, have a seven-month-old son, who has found lodgings with his mother in the Red Cross Young Parents accommodation service.From the age of two, Liana Johansen, 18, lived in foster care and refuges. Now she is living with her 11-month-old daughter in their own place - the first Liana has been able to call home.This week is National Homeless Persons' Week, and the experiences of these three are shared by thousands every night.Liana is open about her past, but has a reason to want more from life. Her mother, grandmother and great-grandmother all had their children taken from them, but Liana says she wants something different for her daughter Summar.''I didn't want to lose my daughter and I didn't want to repeat the cycle,'' she said. ''It wasn't a nice way to be brought up. All I ever wanted was a family and a home.''Alicia left home before her son was born, and he was taken into care while she found a permanent place. Now they live at the Randwick centre, while Luke struggles to find a place to sleep. ''Every night I'm on a new couch,'' he said. ''Sometimes I hit the street for a night. Probably at about 3.30am, 4am I start walking to get to Randwick as the sun is rising.''In a few months the family will be placed in outreach housing and have their own home.''It means a bed. I wouldn't have to run around looking for somewhere to sleep,'' says Luke.The director of the Australian Housing and Urban Research Institute's Western Australia Research Centre, Paul Flatau, is the project leader for one of the largest studies of homelessness.It found 44 per cent of respondents first experienced homelessness before turning 12, and nearly 75 per cent experienced it before turning 18.A fifth said they had slept on the streets before the age of 12, and close to half had slept rough before turning 18.Intergenerational homelessness is also high. About half said one or both of their parents had experienced homelessness of one kind or another.Dr Flatau, who is also associate professor of economics at Murdoch University, said the results revealed there was no single pathway into homelessness.''In order to break the cycle of homelessness, it is important from a policy perspective to identify and understand the circumstances in which intergenerational homelessness is likely to occur and to develop policy and programmatic responses that will reduce the chances of homelessness being experienced across the generations,'' he said. ''This involves not only working with children at risk of experiencing homelessness as adults, but also the parents of these children.''