In family-based analysis, one single-nucleotide polymorphism (SNP; rs1143629, interleukin ( IL1B) 1β) was associated with observed child distress at Bonferroni-corrected levels of significance ( p = .00013), while two approached significance for association with high state anxiety (rs6330Nerve Growth Factor, Beta Subunit, [ NGFB]) and high trait anxiety (rs6265 brain-derived neurotrophic factor [ BDNF]).