A fundamental concern in studying social inequalities is understanding how socioeconomic advantages and disadvantages are passed down from generation to generation. However, previous studies have not adequately distinguished between the contributions of genetic and environmental factors to socioeconomic disadvantage. In this paper, we use Finnish register data on twins born from 1975 to 1986, considering a total of 7,628 pairs, to analyze how genetic and environmental factors are associated with dropout from secondary education, unemployment, and the receipt of social assistance during early adulthood. The results of the twin design show that not only environmental but also genetic factors play a role in all measured socioeconomic disadvantage outcomes. For school dropout and, particularly, unemployment, genetic components explain more than shared environment. Conversely, for the receipt of social assistance, the shared environment component is larger than the genetic component. This result indicates that living in impoverished economic conditions is more dependent on factors related to social resources than those related to genetic inheritance. Of all the measured indicators, the unique environment is the most important, indicating the influence of stochastic life events regarding socioeconomically disadvantageous outcomes.