A study of possible associations between single nucleotide polymorphisms in the estrogen receptor 2 gene and female sexual desire.

INTRODUCTION: Female sexual desire and arousal problems have been shown to have a heritable component of moderate size. Previous molecular genetic studies on sexual desire have mainly focused on genes associated with neurotransmitters such as dopamine and serotonin. Nevertheless, there is reason to believe that hormones with more specific functions concerning sexuality could have an impact on sexual desire and arousal. AIM: The aim of the present study was to investigate the possible effects of 17 single nucleotide polymorphisms (SNPs) located in estrogen receptor genes on female sexual desire and subjective and genital arousal (lubrication). Based on previous research, we hypothesized that ESR1 and ESR2 are relevant genes that contribute to female sexual desire and arousal. MAIN OUTCOME MEASURES: The desire, arousal, and lubrication subdomains of the Female Sexual Function Index self-report questionnaire were used. METHODS: The present study involved 2,448 female twins and their sisters aged 18-49 who had submitted saliva samples for genotyping. The participants were a subset from a large-scale, population-based sample. RESULTS: We found nominally significant main effects on sexual desire for three ESR2 -linked SNPs when controlled for anxiety, suggesting that individuals homozygous for the G allele of the rs1271572 SNP, and the A allele of the rs4986938 and rs928554 SNPs had lower levels of sexual desire. The rs4986938 SNP also had a nominally significant effect on lubrication. No effects for any of the SNPs on subjective arousal could be detected. CONCLUSIONS: The number of nominally significant results for SNPs in the ESR2 gene before correcting for multiple testing suggests that further studies on the possible influence of this gene on interindividual variation in female sexual functioning are warranted. In contrast, no support for an involvement of ESR1 was obtained. Our results should be interpreted with caution until replicated in independent, large samples.

Men's sexual interest in children: one-year incidence and correlates in a population-based sample of Finnish male twins.

In a study of 1,310 Finnish adult male twins we found that sexual interest in children aged 12 or younger was reported by 0.2% of the sample. Sexual interest in children aged 15 or younger was reported by 3.3%. Participants reporting sexual interest in children aged 15 or younger were younger, reported stronger sexual desire, and had experienced more childhood sexual and nonsexual abuse. The present study is the first to give a population-based estimate of the incidence of sexual interest in children among adult men. The 12-month incidence of sexual interest in children below the age of 16 years is roughly comparable to the one-year incidence of major depression or the lifetime prevalence of transvestitic fetishism.

Finnish women and men who self-report no sexual attraction in the past 12 months: prevalence, relationship status, and sexual behavior history.

The aim of the present study was to investigate the prevalence of not reporting sexual attraction in the past year and its associations with factors related to partner relations as well as sexuality-related characteristics in a population-based sample of Finnish twins. The present study was based on a total of 3,540 participants (1,304 men and 2,236 women) aged 33-43 years. A total of 19 men and 73 women reported complete absence of sexual interest in women or men during the past year. Older age was associated with absence of sexual interest in the past year in women, but not men. Individuals who reported absence of sexual interest in the past year were more likely than individuals who reported sexual interest to be single, but those who were in a relationship did not express more dissatisfaction with their relationships. Individuals who reported absence of sexual interest in the past year had had fewer sexual partners and reported less experience of sexual behavior in childhood. Women who reported no sexual interest in the past year, but who were nevertheless sexually active, reported higher frequencies of sexual dysfunctions than matched controls. No significant differences regarding the tendency to fake orgasm were found between the sexually active individuals who reported absence of sexual interest in the past year and the group of matched controls. The present study suggests that absence of sexual interest may be a lifelong phenomenon which does not necessarily affect relationship satisfaction, but is associated with variation in sexual behaviors.

The Genetics of Sexuality and Aggression (GSA) twin samples in Finland.

The Genetics of Sexuality and Aggression (GSA) project was launched at the Abo Akademi University in Turku, Finland in 2005 and has so far undertaken two major population-based data collections involving twins and siblings of twins. To date, it consists of about 14,000 individuals (including 1,147 informative monozygotic twin pairs, 1,042 informative same-sex dizygotic twin pairs, 741 informative opposite-sex dizygotic twin pairs). Participants have been recruited through the Central Population Registry of Finland and were 18-49 years of age at the time of the data collections. Saliva samples for DNA genotyping (n = 4,278) and testosterone analyses (n = 1,168) were collected in 2006. The primary focus of the data collections has been on sexuality (both sexual functioning and sexual behavior) and aggressive behavior. This paper provides an overview of the data collections as well as an outline of the phenotypes and biological data assembled within the project. A detailed overview of publications can be found at the project's Web site: http://www.cebg.fi/.

Are single nucleotide polymorphisms in the oxytocin and vasopressin 1A/1B receptor genes likely candidates for variation in ejaculatory function?

UNLABELLED: What's known on the subject? and What does the study add? There is also evidence that the etiology of premature ejaculation is partially genetic. So far, all molecular genetic studies of premature ejaculation have focused on serotonergic and dopaminergic genes. Serotonergic and dopaminergic neurotransmission aside, studies on both animals and humans have shown that both oxytocin and vasopressin are also involved in ejaculatory function. The present study is, to our knowledge, the first to investigate effects of polymorphisms in oxytocin and vasopressin receptor genes on ejaculatory function. Although a large sample (1517 men) was available for the present study, we could not detect any clear-cut effects of any gene variant on ejaculatory function. We detected a heterozygote effect of one polymorphism (rs75775) in the oxytocin receptor gene. Rare variants of the vasopressin receptor 1A gene may theoretically have a stronger impact on ejaculatory function, but would need a very large sample in order to be established. Based on our results, we conclude that the oxytocin and vasopressin receptor genes are unlikely targets for successful pharmacogenetic interventions. OBJECTIVES: • To investigate associations between single nucleotide polymorphisms (SNPs) linked to the oxytocin, and arginine vasopressin 1A and 1B receptor genes and ejaculatory function. • To investigate these associations in a large, population-based sample. PATIENTS AND METHODS: • In all, 1517 male twins and non-twin brothers of twins aged 18-45 years (mean = 26.43; sd = 4.87) provided questionnaire data regarding ejaculatory function and relevant covariates and saliva samples for genotyping. • A Bayesian linear mixed-effects model, which appropriately controls for between-subjects dependence, was used to estimate genotype associations. • We corrected for multiple testing using a linkage disequilibrium correlation measure. RESULTS: • We found a heterozygote effect on one SNP in the oxytocin receptor gene (rs75775), so that individuals heterozygous for this SNP had significantly elevated risk for premature ejaculation symptoms compared with carriers of either homozygote. • Several SNPs in the arginine vasopressin receptor genes had rare or very rare genotypes. This study may be underpowered to detect potential effects of rare genotypic variants in arginine vasopressin receptor genes. CONCLUSIONS: • Our results regarding the oxytocin receptor polymorphisms support previous studies that indicate a complex relationship between oxytocin and ejaculatory function. • Oxytocin receptor genes are, for example, unlikely suitable targets for pharmacogenetic intervention studies. • Rare variants in arginine vasopressin receptor genes may have significant effects on premature ejaculation, but would need larger sample sizes or case-control designs to be detected.

Disordered eating and gender identity disorder: a qualitative study.

The association between disordered eating and gender identity was examined in a sample of 20 (11 female-to-male, 9 male-to-female) transgender Finnish adults, aged 21-62 years. Using semi-structured interviews, participants' own understanding of the underlying causes of their disordered eating was analyzed, as well as the effect of gender reassignment on eating behaviors and cognitions. A majority of the participants reported current or past disordered eating. Participants most frequently described strive for thinness as an attempt to suppress features of one's biological gender, or accentuate features of one's desired gender. Gender reassignment was primarily perceived as alleviating symptoms of disordered eating.

Testing causal models of the relationship between childhood gender atypical behaviour and parent-child relationship.

An association between childhood gender atypical behaviour (GAB) and a negative parent-child relationship has been demonstrated in several studies, yet the causal relationship of this association is not fully understood. In the present study, different models of causation between childhood GAB and parent-child relationships were tested. Direction of causation modelling was applied to twin data from a population-based sample (n= 2,565) of Finnish 33- to 43-year-old twins. Participants completed retrospective self-report questionnaires. Five different models of causation were then fitted to the data: GAB → parent-child relationship, parent-child relationship → GAB, reciprocal causation, a bivariate genetic model, and a model assuming no correlation. It was found that a model in which GAB and quality of mother-child, and father-child relationship reciprocally affect each other best fitted the data. The findings are discussed in light of how we should understand, including causality, the association between GAB and parent-child relationship.

Genetic and environmental effects on the continuity of ejaculatory dysfunction.

OBJECTIVES: To investigate temporal continuity in ejaculatory dysfunction by comparing self-reported experiences of premature ejaculation (PE) at first intercourse with self-reported PE and delayed ejaculation at present, and to clarify whether and to what extent genetic or environmental factors affect continuity in ejaculatory dysfunction, as previous studies indicate moderate heritability for PE at first intercourse. SUBJECTS AND METHODS: The study comprised retrospective self-reported data on ejaculatory performance at first sexual intercourse and a concurrent self-report of the same at the time of data collection in a population-based sample of 2633 Finnish twins and their siblings aged 18-48 years (mean 26.63, sd 4.68). The continuity of ejaculatory function was assessed by correlation and multiple regression. Reasons for continuity were separated into genetic and environmental sources using twin-model fitting. RESULTS: Ejaculatory function, particularly PE, was stable over time. Genetic effects accounted for approximately 30% of the variance in PE both at first intercourse and when measured at data collection. Unshared environmental effects accounted for most of the variance ( approximately 70%). Genetic effects were almost identical between the sample occasions, but there was a substantial discrepancy between unshared environmental effects affecting PE at first intercourse and unshared environmental effects affecting PE later in life. Age effects were generally negligible. Data were self-reported and retrospective, and thus vulnerable to response bias. CONCLUSIONS: Ejaculatory dysfunction seems to be temporally stable both in the short and long term. Genes that contribute to the variance in PE at first intercourse are similar to those that contribute to the variance in PE later in life, whereas there are, in this regard, substantial differences in the unshared environmental factors that are a cause of PE.

Is there an association between same-sex sexual experience and ejaculatory dysfunction?

Potential effects of sexual orientation on ejaculatory function have been overlooked in the literature. In anticipation of the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V), attempts have been made to formulate universally suitable definitions for different subtypes of premature ejaculation. However, the proposed definitions are centered around intravaginal ejaculation latency time, and little consideration has been given to whether such definitions are applicable to gay or bisexual men. The present study aimed to investigate effects of sexual orientation on premature and delayed ejaculation. When differences in frequencies and patterns of sexual activities were controlled for, there remained no significant effects of sexual orientation on ejaculatory dysfunction.

Childhood sexual interactions with other children are associated with lower preferred age of sexual partners including sexual interest in children in adulthood.

Associations between childhood sexual interactions with other children, and preferred and actual age of sexual partners, as well as adults' sexual interest in children, were explored in a sample of 1312 Finnish male twins. Experience of sexual interaction with other children was associated with lower minimum age of preferred and actual sexual partners in adulthood. In addition, such interactions were connected to an increased likelihood of adults' sexual interest in children under the age of 16 years. None of the participants who reported no such interactions had sexual interest in children in adulthood. In addition, the presence of a female co-twin was associated with higher levels of childhood sexual interactions and lower minimum age of preferred and actual sexual partners. Finally, the extent of childhood sexual interactions was not affected by genetic factors, suggesting that the identified association represents true environmental causation. Experiences of childhood physical and sexual abuse were positively related to the extent of the childhood sexual interactions with other children. The results support the role of conditioning in the development of sexual age preferences.

Common genetic effects of gender atypical behavior in childhood and sexual orientation in adulthood: a study of Finnish twins.

The existence of genetic effects on gender atypical behavior in childhood and sexual orientation in adulthood and the overlap between these effects were studied in a population-based sample of 3,261 Finnish twins aged 33-43 years. The participants completed items on recalled childhood behavior and on same-sex sexual interest and behavior, which were combined into a childhood gender atypical behavior and a sexual orientation variable, respectively. The phenotypic association between the two variables was stronger for men than for women. Quantitative genetic analyses showed that variation in both childhood gender atypical behavior and adult sexual orientation was partly due to genetics, with the rest being explained by nonshared environmental effects. Bivariate analyses suggested that substantial common genetic and modest common nonshared environmental correlations underlie the co-occurrence of the two variables. The results were discussed in light of previous research and possible implications for theories of gender role development and sexual orientation.

Prevalence and determinants of male sexual dysfunctions during first intercourse.

We explored the balance of genetic and environmental factors on sexual dysfunctions during first intercourse experience in young men. Gender role conflict theory predicts that young males should show high levels of such dysfunctions coupled with mixed affective reactions. Three thousand one hundred eighty six male twins and their siblings (M = 26.17 years, SD = 4.77) completed items on erectile dysfunction (ED), premature ejaculation (PE), contextual factors, and affective reactions during first intercourse, as well as parental attitudes towards nudity and sexuality. Twin modeling revealed a significant genetic effects for PE, but not for ED. Experiences of sexual dysfunction and both negative and positive affects during first intercourse were common among the participants. More positive parental attitudes were associated with less dysfunction and more positive affect during first intercourse. Having the first sexual intercourse with an unknown partner and while strongly intoxicated were, together with group pressure and reluctance to engage in intercourse, related to more negative and less positive affects. Erectile dysfunction during the first intercourse was related to more negative and less positive affects.

The adult body: how age, gender, and body mass index are related to body image.

OBJECTIVE. Body image and perceived attractiveness were examined, and the impact of age, gender, and body mass index (BMI) was analyzed and discussed from an evolutionary and a sociocultural perspective. METHOD. The population-based sample consisted of 11,468 Finnish men and women aged 18 to 49 years. RESULTS. Both age-related decrease and increase in body satisfaction was detected as well as interactions between age and gender. Some effects were nonlinear. Women were generally less satisfied with their bodies than men. BMI had a stronger influence on women's body image than men's. DISCUSSION. It was proposed that it is insufficient to merely study how age affects general body image because adults might become more satisfied with some aspects of their bodies as a function of age and less satisfied with other aspects. Body satisfaction might also fluctuate during different phases of the adult life, and the patterns possibly differ between men and women.

Exploring genetic and environmental effects in dysphonia: a twin study.

PURPOSE: To explore the existence of genetic effects as well as the interaction between potential genetic effects and a voice-demanding occupation on dysphonia. METHOD: One thousand seven hundred and twenty-eight Finnish twins (555 male; 1,173 female) born between 1961 and 1989 completed a questionnaire concerning vocal symptoms and occupation. The zygosity determination resulted in 125 monozygotic and 108 dizygotic full twin pairs. A composite variable called dysphonia was formed by summing 6 vocal symptoms based on the results of a factor analysis. Twin model fitting was used to explore the contribution of genetic and environmental effects on the dysphonia variable. RESULTS: Individual differences in dysphonia were explained by genetic effects (35%) and nonshared environmental effects (65%). Shared environmental effects were estimated at 0%. Also, the authors found that for the participants who worked in voice-demanding occupations, the causes of dysphonia were more environmental, whereas the etiology of the symptoms was more strongly affected by genes in the participants with less voice-demanding occupations. However, this gene-environment interaction was not statistically significant. CONCLUSION: Both genetic and environmental factors have an impact on the etiology of voice problems. Environmental factors, either independently or interacting with genetic factors, seem to play the key role, especially if the person has a voice-demanding occupation.

Potential for homosexual response is prevalent and genetic.

We investigated the potential to engage in homosexual behavior in 6001 female and 3152 male twins and their siblings finding that 32.8% of the men and 65.4% of the women reported such potential (p<0.001). 91.5% of these men and 98.3% of these women reported no overt homosexual behavior during the preceding 12 months. The potential to engage in homosexual behavior was influenced by genetic effects for both men (37.4%) and women (46.4%) and these overlapped only partly with those for overt homosexual behavior.

Female sexual function and its associations with number of children, pregnancy, and relationship satisfaction.

Associations between number of children, pregnancy, and overall relationship satisfaction were explored in a population-based sample of 2081 women, aged 33-43 years. Multiparous women had less orgasm problems compared to nulliparous women. Nulliparous women had more pain problems and were sexually less satisfied compared to women with children, regardless of the number. Women pregnant with the first child had fewer pain problems compared to a matched nonpregnant control and were sexually more satisfied. Being more satisfied with the overall relationship was related to higher sexual satisfaction and less sexual function problems.

Evaluation of the female sexual function index in a population based sample from Finland.

The factor structure and reliability of the Female Sexual Function Index (FSFI) was evaluated in a Finnish population based sample of 2,081 women, age 33-43 years. In addition, associations between female sexual function and age, psychological distress, alcohol use, hormone based contraceptives, child sexual abuse (CSA), and adult sexual abuse were examined. The results supported a six factor solution for the FSFI with high internal consistencies, in line with earlier research in clinical populations. Psychological distress was positively associated with every dimension of the FSFI except desire problems. Age was associated with fewer pain problems. Alcohol use was associated with every dimension of the FSFI, but the direction of the association depended on if it was drinking in general or in connection to intercourse. More drinking in general was related to fewer sexual function problems while drinking in connection to intercourse was related to more sexual function problems. No significant correlation was found between adult sexual abuse and sexual function but between CSA and lubrication, satisfaction, and pain problems. Usage of oral contraceptive pill was not significantly associated with sexual function. The use of hormone based intrauterine systems was significantly associated with less pain and more desire, arousal, and satisfaction. In conclusion, the study supports use of the FSFI for assessing sexual function not only in clinical samples but also in population based samples. The associations found between sexual function and other important variables showed the complexity of sexual function.

Genetic effects on male sexual coercion.

The genetic and environmental influences on sexual coercion, and to what extent its associations with alcohol use and psychopathy depend on shared genetic and environmental effects, were explored in a Finnish population-based sample of 938 men, aged 33-43 years, using the classical twin study design. All three phenotypes were associated positively and affected by genes (sexual coercion 28%, alcohol use 60%, psychopathy 54%), with 46% of the correlation between sexual coercion and psychopathy, 89% of the correlation between alcohol use and psychopathy and 100% of the correlation between sexual coercion and alcohol use being explained by shared genetic effects. Further, the results showed that a proportion of the variance in sexual coercion was derived from a highly genetic source that was common with alcohol use and psychopathy. This latent factor was hypothesized to reflect a general tendency for antisocial behavior that is pervasive across different situations. Relevant theories on sexual coercion were discussed in light of the results.

Gene-Environment Correlation Between the Dopamine Transporter Gene (DAT1) Polymorphism and Childhood Experiences of Abuse.

In the present study, we investigated the possible gene-environment correlation between the dopamine transporter gene (DAT1) polymorphism and childhood experiences of abuse and neglect. Genetic information was obtained from 1,442 male and 2,178 female twins and their siblings drawn from a Finnish population-based sample. The Childhood Trauma Questionnaire was used to measure the childhood experiences of abuse and neglect. In men, the DAT1 polymorphism was associated with having experienced sexual abuse in childhood, such that men with the 9R9R genotype reported less sexual abuse experiences than men with the 9R10R or the 10R10R genotypes. In women, there was an association between the DAT1 polymorphism and childhood experiences of emotional abuse, such that women with the 9R9R genotype reported less emotional abuse experiences than women with the 9R10R or 10R10R genotypes. No other associations between the DAT1 polymorphism and childhood experiences of abuse and neglect were found. In sum, the results suggested that some genetic components might predispose children to experience childhood abuse and neglect. Possible reasons for this association were discussed.

Genetic and environmental effects on sexual excitation and sexual inhibition in men.

The Sexual Inhibition and Sexual Excitation Scales (SIS/SES) measure the propensity for sexual inhibition and excitation in men. According to the theoretical model underlying the SIS/SES, sexual response and associated behavior depend on dual control mechanisms in the brain involving the balance of excitatory and inhibitory systems which impinge on sexual response. Previous research with the SIS/SES has indicated one higher-order excitatory factor and two higher-order inhibitory factors affecting sexual response. The present study analyzed the item structure and the psychometric properties of the instrument in a population based sample of Finnish male twins (N = 1,289), and, including 37 out of 45 items of the original scales, estimated the heritability of and the environmental influences on the excitatory and inhibitory mechanisms. The twin correlations and the structural equation modeling suggested modest heritability for both inhibitory mechanisms. Sexual excitation, in contrast, was not influenced by genetic effects and similarities between twins for this mechanism seemed to be caused by the common environment of the twins.