Firstly, associations between 12 SNPs in the oxytocin receptor gene (OXTR) and measures of pair-bonding were investigated in the TCHAD and TOSS samples, comprising men and women in romantic relationships (see Tables 2 and 3 for the results from these analyses ). Secondly, the SNP positively associated with pair-bonding behavior in women in the first step (rs7632287) was further studied in relation to marital crisis and measures of marital quality as perceived by spouses in the TOSS sample (Table 4a,b). Thirdly, the relation between behaviors in young girls and adult pair-bonding behavior was explored using the longitudinal design in TCHAD (Table 4c). The CBCL subscale social problems at age 8–9 was revealed to predict pair-bonding behavior in adulthood. Fourthly, the rs7632287 SNP was studied in relation to the social problems scale in TCHAD. The CBCL social problems scale has previously been shown to be associated with measures of the autism spectrum (65) and in the final step the rs7632287 SNP was studied in relation to symptoms of autism assessed in an additional sample, CATSS (Table 5). See text for further details and references regarding the samples and the different measures. Sample names are in bold text. RQS=Relationship Quality Survey, PBS=Partner Bonding Scale, CBCL=Child Behavior Checklist, A-TAC= the Autism—Tics, AD/HD, and other Comorbidities inventory.