Genes (Biological) -> Schizophrenia is a genetic illness, a gene or genes can be passed down from parents to children.
Predicts Schiz runs in families.
Gottesman (1991) found a concordance rate between MZ twins with 48% but only 17% in DZ twins. Meaning if one pair of MZ twins have Schiz; there is a 48% chance that the other twin will also have it. Jospeh (2004) – pooled data for all Schiz twins’ studies carried out prior to 2001 shows a concordance rate for MZ of 40.4% & 7.4% for DZ. = convincing evidence that schizophrenia does have a genetic basis.
Adoption Studies: to overcome issues of shared genes and environment you can look at concordance rates between adopted and birth family.
Tienari (2002) Studied 164 adoptees whose biological mothers had been diagnosed with Schiz = 12 also received schiz diagnosis, compared with 4/197 control adoptees born to non-schiz mothers. H! Children who are at a high genetic risk…