strength - support for diathesis stress model- A study of 13,000 danish adoptees was conducted by Mendrick (1984). When neither biological parents nor adoptive parents had convictions, the percentage of adoptees with convictions was 13.5% which is quite high. This figure rose to 20% with at least one parent with convictions and 24.5% with both parents having convictions. Shows genetic inheritance plays a role but environmental influence is also important, providing support for diathesis stress model.