Table 3 -.
Studies on behavioral traits in opposite-sex and same-sex twins
| Trait | Publication | Setting | Numbers of opposite-sex (OS) and same-sex (SS) twins | Is there a comparison between OS and SS dizygotic (DZ) twins only?a | Age | Assessment | Findings OS vs. SS females | Findings OS vs. SS males | Suggests evidence for masculiniza-tion of OS femalesb | Suggests evidence for demasculiniza-tion of OS malesb |
|---|---|---|---|---|---|---|---|---|---|---|
| Alcohol use | Lenz et al., 2012 | A Sweden B Australia |
Sample A: 29,933 females 29,271 males Sample B: 2,041 males 3,848 females (Breakdown not provided) |
Yes | Not provided | Hospitalization rate due to alcohol dependence from the Swedish Twin Registry. Self-reported lifetime prevalence of alcohol dependence obtained from telephone interviews | No significant differences | Higher prevalence of alcohol dependence for OSM than SSM | − | + |
| Ellingson et al., 2013 | Australia | 621 OSF 915 SSF (DZ) 1,191 SSF (MZ) |
No | 32–43 years, mean = 37.7 years | Self-reported alcohol use, alcohol dependence and abuse symptoms obtained from telephone interviews | OSF slightly more lifetime alcohol use disorder (AUD) symptoms than SSF. No other differences | NA | +/− | NA | |
| Autistic symptoms/hyperactivity disorder (ADHD) | Ho et al., 2005 | Missouri, USA | 250 OSF 142 SSF (DZ) 177 SSF (MZ) 250 OSM 128 SSM (DZ) 91 SSM (MZ) |
Yes | 7–15 years | Parent report: sub-threshold autistic symptomatolo-gy assessed using the Social Responsive-ness Scale (SRS) | No significant differences | OSM lower mean score on the SRS (indicating less autistic symptomatolo-gy) compared with SSM | − | + |
| Atterman et al., 2012 | Denmark | 2947 OSF 3412 SSF |
Yes | 3–15 years | Parental responses to items from the Child Behaviour Checklist (CBCL) | OSF scored lower than SSF for both ADHD and total scores – contrary to expected | NA | − | NA | |
| Eriksson et al., 2016 | Sweden | 4219 OSF 1808 SSF (DZ) 4219 OSM 2129 SSM (DZ) |
DZ twins only | 9 or 12 years | Parental telephone interview examining attention-deficit/hyperactivity disorder (ADHD) and autistic traits using Autism-Tics, AD/HD, and other Comorbidities Interventory (ATAC) | OSF displayed fewer traits related to attention deficit and repetitive and stereotyped behaviors than SSF – opposite to what was expected | OSM displayed a larger number of traits related to attention deficit and repetitive and stereotyped behaviors than SSM | − | − | |
| Disordered eating (DE) | Culberg et al., 2008 | Michigan, USA | 59 OSF 132 SSF (DZ) 172 SSF (MZ) 54 OSM 62 SSM (DZ) 103 SSM (MZ) |
Yes | Mean = 20.8 years | Self-report from the Minnesota Eating Behavior Survey | Less DE for OSF compared with SSF | More DE for OSM compared with SSM | + | + |
| Raevuori et al., 2008 | Finland | 793 OSF 765 SSF (DZ) 868 SSF (MZ) 717 OSM 705 SSM (DZ) 540 SSM (MZ) |
Yes | 22–28 years, mean = 24.4 years | Self-reported current and lifetime diagnoses of anorexia nervosa and bulimia nervosa obtained from Structured Clinical Interview for DSM-IV – short version by telephone | No significant differences | No significant differences | − | − | |
| Baker et al., 2009 | Sweden | 371 OSF 213 SSF (DZ) 439 SSF (MZ) 361 OSM 344 SSM (DZ) 461 SSM (MZ) |
Yes | 15–17 years | Self-report from Eating Disorder Inventory-2 (questionnaire) | No significant differences | No significant differences | − | − | |
| Lydecker et al., 2012 | A: Virginia, USA B: Norway C: Sweden |
Sample A: 481 OSF 408 SSF (DZ) 614 SSF (MZ) 317 OSM 295 SSM (DZ) 492 SSM (MZ) Sample B: 345 OSF 530 SSF (DZ) 900 SSF (MZ) 341 OSM 235 SSM (DZ) 445 SSM (MZ) Sample C: 2433 OSF 2901 SSF (DZ) 4099 SSF (MZ) 2423 OSM 1918 SSM (DZ) 2684 SSM (MZ) |
Yes | A: Females: mean = 40.4 years Males: mean = 42.3 years B: Females: mean = 28.2 years Males: mean = 28.3 years C: Females: mean = 33.5 years Males: mean = 33.4 years |
Self-reported eating disorders from interviews based on DSM-IV criteria | No significant differences when comparing OS and SS (DZ) twins but co-twin sex was associated with broadly defined bulimia nervosa in sample C when MZ twins were included | No significant differences | − | − | |
| Culbert et al., 2013 | Michigan, USA | 64 OSF 178 SSF |
No | Pre-Early puberty OSF: mean = 11.7 years, SSF: mean = 11.4 years Mid-Late puberty OSF: mean = 14.0 years SSF: mean = 13.2 years |
Self-reported DE attitudes assessed by the Minnesota Eating Behavior Survey and the Eating Disorder Examination Questionnaire | OSF exhibited lower levels of DE attitudes (more masculinized) during mid-late puberty compared with SSF. No significant differences during pre-early puberty | NA | +/− | NA | |
| Feminity - masculinity | Loehlin and Martin, 2000 | Australia | Sample A: 691 OSF 3158 SSF 634 OSM 1390 SSM Sample B: 447 OSF 1773 SSF 399 OSM 1041 SSM |
No | A: 24–87 years, mean = 41.2
years B: 1728 years, mean = 23.2 years |
Masculini ty-femininity scales “Worried”, “Reserved” and “Breaks Rules” scales, derived from the Eysenck Personality Questionnaire and Cloninger Tridimensional Personality Questionnaire (short versions) | A: No significant differences B: OSF higher scores on Breaks-Rules subscale than SSF but not on the other subscales |
A: OSM higher than SSM on Worried
subscale and Breaks-Rules subscale but not for Reserved
subscale. B: OSM higher than SSM on the Breaks-Rules subscale. No significant difference on Worried and Reserved subscale |
+/− | +/− |
| Feminity – masculinity/Pubertal development/Fertility in early adulthood | Rose et al., 2002 | Finland | 972 OSF 967 SSF 931 OSM 1060 SSM Sample A: 783/486 OSF 762/466 SSF Sample B: 772/464 OSF 749/454 SSF (Number of males not provided) Sample C: 4767 OSF 7528 SSF |
No | 16 years A: 11 years B: 14 years (follow up) C: 15–28 years |
Self-report from Feminine Interest (FEM)
Scale A and B: Post-menarche frequencies. B: Self-reported Pubertal Development Scale (females and males) C: Fertility in early adulthood from Central Population Records |
No significant differences | No significant differences | − | − |
| Verweij et al., 2016 | Sweden | 536 OSF 392 SSF (DZ) 695 SSF (MZ) 536 OSM 248 SSM (DZ) 374 SSM (MZ) |
No | 27–54 years, mean = 40.7 years | Self-reported Big-Five personality inventory data used to create a bipolar masculinity-femininity (M-F) scale | OSF scored higher (more masculine) on the M-F scale than SSF | OSM scored higher (more masculine) on the M-F scale than SSM | + | − | |
| Masculine Attitudes (Conservatism) | Miller and Martin, 1995 | Australia | 905 OSF 3964 SSF 905 OSM 1832 SSM |
No | Adults | Self-report from Wilson–Patterson Conservatism Scale (questionnaire) | OSF reported more masculine (socially conservative) views compared with SSF | No significant differences | + | − |
| Religiousness and religious coping | Ahrenfeldt et al., 2016 | Denmark | 408 OSF 1383 SSF 350 OSM 856 SSM (Number of MZ twins not provided) |
Yes – comparison between OS and SS (DZ)+UZ twins | 20–40 years, mean = 29.8 years | Self-reported survey including questions on religiousness and religious coping | No significant differences | No significant differences except that OSM reported attending church more often than SSM in childhood | − | − |
| Sensation seeking/agression | Resnick et al., 1993 | England | 51 OSF 286 SSF 51 OSM 85 SSM |
No (scores for MZ and SSDZ twins did not differ) | 16–70 years | Self-report from Sensation Seeking Scale IV (SSS-IV) – an overall score and four subscales scores (questionnaire) | OSF reported increased disinhibition, experience seeking and overall sensation seeking compared with SSF | No significant differences | +/− | − |
| Cohen-Bendahan et al., 2005a | The Netherlands | 74 OSF 55 SSF |
DZ twins only | 13 years | Self-report from Sensation Seeking Scale V
(SSS-V) questionnaire and from Olweus Multifaceted Aggression Inventory
(OMAI) Test of child: Reinisch Aggression Inventory (RAI) |
OSF lower experience seeking behavior – opposite to expected. OSF rated more aggressive than SSF on two of the RAI but no differences on OMAI subscales | NA | −/+ | NA | |
| Slutske et al., 2011 | Australia | 564 OSF 836 SSF (DZ) 1,111 SSF (MZ) |
Yes | 32–43 years, mean = 37.7 years | Telephone interview and questionnaire: The Zuckerman Sensation Seeking Scale-Form V (SSS-V) | OSF showed higher experience-seeking and thrill- and – adventure seeking scores compared with SSF. Other group differences were non-significant | NA | +/− | NA | |
| Sex-typed play | Elizabeth and Green, 1984 | New York and Long Island area | 156 OSF 270 SSF (DZ) 320 SSF (MZ) 156 OSM 240 SSM (DZ) 262 SSM (MZ) |
Yes | 4–12 years, mean = 6.8 years | Parental report: a 17-item questionnaire used to discriminate between typical and atypical sex-role development | No significant differences | OSM scored in a more feminine direction compared with SSM | − | + |
| Henderson and Berenbaum, 1997 | Illinois, USA | 35 OSF 36 SSF |
DZ twins only | 3–8 years, OSF: mean = 5.1
years SSF: mean = 5.5 years |
Observational: time child played with toys typically preferred by boys/girls. Mothers’ reports of game preferences | No significant differences | NA | − | NA | |
| Rodgers et al., 1998 | Oregon, USA | 16 OSF 54 SSF 16 OSM 48 SSM |
DZ twins only | 7–12 years, OS: mean = 8.3
years SSF: mean = 8.1 years SSM: mean = 8.5 years |
Observational: toy preferences during 5-minute free-play interactions between mothers and twins | No significant differences | No significant differences | − | − | |
| Social skills | Laffey-Ardley and Thorpe, 2006 | Australia | 36 OSF 28 SSF (DZ) 36 OSM 22 SSM (DZ) |
DZ twins only | 3–6 years, OS: mean = 4.4
years SS: mean = 4.7 years |
Parent and teacher reports of social co-operation and compete nce using the Preschool and Kindergarten Behavior Scale – 2nd Edition (PKBS-2) | Parent reports: Mixed result for social co-operation: OSF rated higher than SSF when using adjusted ANCOVA analysis but not for simple ANOVA analysis | Teacher-reports: SSM rated higher than OSM on social co-operation | +/− | − |
NA: Not available, OS: opposite-sex, SS = same-sex, F = females, M = males, MZ = monozygotic, DZ = dizygotic, UZ = unknown zygosity
a
Yes: The study makes a separate comparison of OS vs SSDZ twins, although it includes both MZ and DZ twins.
No: The study does not make a separate comparison of OS vs SSDZ twins, thus, including MZ twins in all analyses.
DZ twins only: The study includes DZ twins only. Thus, no MZ twins are included in the study.
b
+: The study provides evidence for masculinization of OS females/demasculinization of OS males.
−: The study provides no evidence for masculinization of OS females/demasculinization of OS males.
+/−: The study provides evidence for masculinization of OS females/demasculinization of OS males in some cases (e.g. in some investigated measures, in some age groups or in some statistical analyses), but not in all.