Living in cities affects young adults' access to education and work. With the use of register data for 2000-2013, we examined the role of having siblings and parents living close by and having siblings and parents living in the area of origin, in young adults' return migration from the four largest cities in Sweden. We found that young adults were less likely to return, and also less likely to migrate elsewhere, if they had siblings or parents living in the city of residence than if this was not the case. If the parents no longer lived in the region of origin, the young adults were very unlikely to return. Young adults were more likely to return if they had siblings living in that region than if they had no siblings or the siblings lived elsewhere. Adverse circumstances such as dropping out of tertiary education, low income, and unemployment were associated with a greater likelihood of return migration.