Transcript Slide 1
Today’s session You are learning about... You are learning to... • • Biological theories of offending • • Interpret, evaluate and draw conclusions from evidence Transfer concepts and skills from one topic to another Learn effectively from lectures • Later on, I will be giving you a lecture on this. But first, I want you to use your psychological skills of interpretation and evaluation to anticipate what I’m going to tell you. Is there a gene for crime? No. There isn’t. • ‘Lombrosian’ view: – Single defective gene responsible • Modern behavioural genetics: – Polygenetic influences – Complex interactions with environment – No assumption of defect Two questions • Is there a genetic influence on crime? – Family history studies – Twin studies – Adoption studies • If so, how does the influence operate? Family history studies • Osborne & West (1982) – Father has a criminal conviction – 40% of sons do – Father has no criminal conviction – 13% of sons do • Consistent with genetic influence – Also with learning/environment – Suggests genes do not determine criminality Twin studies • Early studies strongly suggested genetic influence but flaws in sampling, determining zygocity. • More recently: – Christiansen (1977): MZ 35%; DZ 13% – Dalgard & Kringlen (1976): MZ 26%; DZ 15% • Low MZ concordances – influence not strong • Confounding effects of more similar treatment for MZ Adoption studies • Generally found that adopted children more similar to biological than adoptive parents. • Supports genetic hypothesis but: – Issue of what is being inherited (e.g. alcoholism) – Could be prenatal influences, not genetic – Age at adoption – early influences? What is being inherited? • Hollin (1992) gives three suggestions: – Abnormal CNS e.g. Low IQ; ADHD – Abnormal ANS e.g. Lack of responsiveness – Abnormal endocrine e.g. Influence of testosterone • Difficult to resolve because of enormous complexity of interactions • Lots of biological correlates of criminality; few obvious causes. • What were the bits you had already worked out? • Which bits were new or unexpected given your own interpretation?