Evidence Relationship: Supports
Vote on whether "Discordant sibling pairs in the Nordic cohort showed no difference in polygenic score for depression (d = 0.02)" is good evidence that supports the claim "Sibling-difference analysis in the Nordic BirthCohort Linkage (n=41,300 full sibling pairs) retained 68% of the adversity-depression association within families"
Evidence Claim
Discordant sibling pairs in the Nordic cohort showed no difference in polygenic score for depression (d = 0.02)
Follow-up genotyping of 6,800 exposure-discordant pairs (Palm et al., 2022) found that the exposed and unexposed sibling did not differ on a depression PGS derived from an independent GWAS. Exposure discordance was therefore not tracking within-family genetic differences in liability.
Main Claim
Sibling-difference analysis in the Nordic BirthCohort Linkage (n=41,300 full sibling pairs) retained 68% of the adversity-depression association within families
Ingebretsen & Palm (2021) linked registry-verified adversity exposures (child protective contact, parental incarceration, documented household violence) to adult ICD-coded depression. Between-family OR was 2.31; the within-sibling-pair OR was 1.89, i.e. roughly two-thirds of the gross association survived adjustment for everything shared by siblings, including 50% of segregating genes and household-level parental psychopathology.
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Current depression PGS captures maybe 3-5% of variance, so balance on PGS is weak evidence of balance on genetic liability overall. Necessary but far from sufficient.
Fair. The honest framing is that it rules out the largest measurable slice of evocative rGE, not all of it.