Wiki says "Genetic factors account for about 70–90% of the risk of developing bipolar disorder." https://www.blackdoginstitute.org.au/resources-support/bipolar

Wiki says "Genetic factors account for about 70–90% of the risk of developing bipolar disorder." https://www.blackdoginstitute.org.au/resources-support/bipolar-disorder/causes/ https://www.blackdoginstitute.org.au/resources-support/bipol... says 80%, and says "If one parent has bipolar disorder, there’s a 10% chance that their child will develop the illness. / If both parents have bipolar disorder, the likelihood of their child developing bipolar disorder rises to 40%." One of the cited papers is "Family, twin, and adoption studies of bipolar disorder". Link that gives only the abstract: https://pubmed.ncbi.nlm.nih.gov/14601036/ https://pubmed.ncbi.nlm.nih.gov/14601036/ I haven't dug into the paper yet, but there's a starting point. Edit: The paper says "More recent (and rigorous) studies that have compared concordance rates specifically of bipolar disorder among MZ [monozygotic] and DZ [dizygotic] twin pairs are summarized in table 2." The table shows four studies that gave concordances of 0.00-0.08 for dizygotic twins, and 0.36-0.75 for monozygotic twins.