Sexuality is central to our individual lives, our society, and our evolution, but its etiology is not thoroughly understood. Using data from 4904 Australian twins who completed a questionnaire on sexual attitudes and behaviours, I investigated the genetic and environmental influences underlying variation in and covariation between psychological and behavioural aspects of sexuality. Moreover, I explored the role of sexuality traits in several different contexts: evolution, mental health, public health, personality, and problematic behaviour. Before presenting reports of the four main empirical studies in this thesis, I make the case for the importance of studying human sexuality, outline previous findings on the etiology of individual differences in sexuality, and describe the behavioural genetic principles and techniques that were used in the investigations. I also present an additional fifth paper reporting a behavioural genetic analysis of EEG power, which I undertook in order to learn twin data modelling and complex multivariate techniques. In the first empirical paper I investigated sexual orientation from an evolutionary perspective. As sexual orientation is genetically influenced, it is not known how homosexuality, which tends to lower reproductive success, is maintained in the population at a relatively high frequency. I tested the hypothesis that while genes predisposing to homosexuality reduce homosexuals’ reproductive success, they may confer some advantage for heterosexuals who carry them. Results showed that psychologically masculine females and feminine men are 1) more likely to be nonheterosexual, but 2) when they are heterosexual have more opposite-sex sexual partners. Genetic modelling revealed that both these relationships are partly due to pleiotropic genetic influences common to each trait. Further, heterosexuals with a nonheterosexual twin had more opposite-sex partners than do heterosexual twin pairs. Taken together, these results suggest that genes predisposing to homosexuality may confer a mating advantage in heterosexuals, which could contribute to the evolution and maintenance of homosexuality in the population. In the second empirical paper I investigated sexual orientation from the perspective of mental health risk. Large epidemiological studies have shown that homosexuals are at much greater risk of psychiatric disorder than the general population. This has been assumed, with some supporting evidence, to be because of the prejudice and discrimination experienced by homosexuals in a heterosexist society. Here I tested the viability of alternative explanations, using Eysenck’s Neuroticism and Psychoticism scales as markers for psychiatric vulnerability. Firstly, I tested whether apparent sexual orientation differences in psychiatric vulnerability simply mirror sex differences – for our traits, this would predict nonheterosexual males having elevated Neuroticism scores as females do, and nonheterosexual females having elevated Psychoticism scores as males do. The results contradicted this idea, with nonheterosexual men and women scoring significantly higher on both Neuroticism and Psychoticism than their heterosexual counterparts, suggesting an overall elevation of psychiatric risk in nonheterosexuals. Secondly, I used the genetically informative sample to assess the viability of explanations invoking a common cause of both nonheterosexuality and psychiatric vulnerability. We found significant genetic correlations between sexual orientation and both Neuroticism and Psychoticism, but no corresponding environmental correlations, suggesting that if there is a common cause of both nonheterosexuality and psychiatric vulnerability it is likely to have a genetic basis rather than an environmental basis. The third empirical paper investigated the etiology of risky sexual behaviour, which is relevant to public health and welfare through its role in STD transmission and unwanted pregnancies. Results showed that variation in risky sexual behaviour is due to genetic, shared environmental, and unshared environmental influences to approximately equal degrees. The genetic influences partly overlapped with genetic influences on dispositional factors, with significant genetic correlations between risky sexual behaviour and Eysenck’s Impulsivity, Extraversion, Psychoticism, and Neuroticism. This suggests that the genetic influences that shape our personality may also predispose us to risky sexual behaviour. The fourth empirical paper investigated the etiology of a strong association (r = .50) between risky sexual behaviour and adolescent misconduct. Results indicated that the association is due to overlapping genetic and environmental influences, but that in males genes are the primary source of the association whereas in females shared environment plays the greater role. These findings suggest that a general predisposition to risky behaviour may manifest in different potentially harmful ways in adolescence (misconduct) and adulthood (risky sexual behaviour), and that different processes are involved in male and female etiology. Following the empirical reports, I provide a general discussion of my research findings and the study of human sexuality more generally. After summarising the findings and their implications, I then provide a detailed description of potential limitations of the research and to what extent they qualify the conclusions drawn. I also critically discuss the absence of sexuality traits from the major models of personality, and why this and other shortcomings make the personality models inadequate from an evolutionary perspective. Finally, I suggest directions for future research in light of the research and discussion presented in this thesis.

Sexuality is central to our individual lives, our society, and our evolution, but its etiology is not thoroughly understood. Using data from 4904 Australian twins who completed a questionnaire on sexual attitudes and behaviours, I investigated the genetic and environmental influences underlying variation in and covariation between psychological and behavioural aspects of sexuality. Moreover, I explored the role of sexuality traits in several different contexts: evolution, mental health, public health, personality, and problematic behaviour. Before presenting reports of the four main empirical studies in this thesis, I make the case for the importance of studying human sexuality, outline previous findings on the etiology of individual differences in sexuality, and describe the behavioural genetic principles and techniques that were used in the investigations. I also present an additional fifth paper reporting a behavioural genetic analysis of EEG power, which I undertook in order to learn twin data modelling and complex multivariate techniques. In the first empirical paper I investigated sexual orientation from an evolutionary perspective. As sexual orientation is genetically influenced, it is not known how homosexuality, which tends to lower reproductive success, is maintained in the population at a relatively high frequency. I tested the hypothesis that while genes predisposing to homosexuality reduce homosexuals’ reproductive success, they may confer some advantage for heterosexuals who carry them. Results showed that psychologically masculine females and feminine men are 1) more likely to be nonheterosexual, but 2) when they are heterosexual have more opposite-sex sexual partners. Genetic modelling revealed that both these relationships are partly due to pleiotropic genetic influences common to each trait. Further, heterosexuals with a nonheterosexual twin had more opposite-sex partners than do heterosexual twin pairs. Taken together, these results suggest that genes predisposing to homosexuality may confer a mating advantage in heterosexuals, which could contribute to the evolution and maintenance of homosexuality in the population. In the second empirical paper I investigated sexual orientation from the perspective of mental health risk. Large epidemiological studies have shown that homosexuals are at much greater risk of psychiatric disorder than the general population. This has been assumed, with some supporting evidence, to be because of the prejudice and discrimination experienced by homosexuals in a heterosexist society. Here I tested the viability of alternative explanations, using Eysenck’s Neuroticism and Psychoticism scales as markers for psychiatric vulnerability. Firstly, I tested whether apparent sexual orientation differences in psychiatric vulnerability simply mirror sex differences – for our traits, this would predict nonheterosexual males having elevated Neuroticism scores as females do, and nonheterosexual females having elevated Psychoticism scores as males do. The results contradicted this idea, with nonheterosexual men and women scoring significantly higher on both Neuroticism and Psychoticism than their heterosexual counterparts, suggesting an overall elevation of psychiatric risk in nonheterosexuals. Secondly, I used the genetically informative sample to assess the viability of explanations invoking a common cause of both nonheterosexuality and psychiatric vulnerability. We found significant genetic correlations between sexual orientation and both Neuroticism and Psychoticism, but no corresponding environmental correlations, suggesting that if there is a common cause of both nonheterosexuality and psychiatric vulnerability it is likely to have a genetic basis rather than an environmental basis. The third empirical paper investigated the etiology of risky sexual behaviour, which is relevant to public health and welfare through its role in STD transmission and unwanted pregnancies. Results showed that variation in risky sexual behaviour is due to genetic, shared environmental, and unshared environmental influences to approximately equal degrees. The genetic influences partly overlapped with genetic influences on dispositional factors, with significant genetic correlations between risky sexual behaviour and Eysenck’s Impulsivity, Extraversion, Psychoticism, and Neuroticism. This suggests that the genetic influences that shape our personality may also predispose us to risky sexual behaviour. The fourth empirical paper investigated the etiology of a strong association (r = .50) between risky sexual behaviour and adolescent misconduct. Results indicated that the association is due to overlapping genetic and environmental influences, but that in males genes are the primary source of the association whereas in females shared environment plays the greater role. These findings suggest that a general predisposition to risky behaviour may manifest in different potentially harmful ways in adolescence (misconduct) and adulthood (risky sexual behaviour), and that different processes are involved in male and female etiology. Following the empirical reports, I provide a general discussion of my research findings and the study of human sexuality more generally. After summarising the findings and their implications, I then provide a detailed description of potential limitations of the research and to what extent they qualify the conclusions drawn. I also critically discuss the absence of sexuality traits from the major models of personality, and why this and other shortcomings make the personality models inadequate from an evolutionary perspective. Finally, I suggest directions for future research in light of the research and discussion presented in this thesis.

Sexuality is central to our individual lives, our society, and our evolution, but its etiology is not thoroughly understood. Using data from 4904 Australian twins who completed a questionnaire on sexual attitudes and behaviours, I investigated the genetic and environmental influences underlying variation in and covariation between psychological and behavioural aspects of sexuality. Moreover, I explored the role of sexuality traits in several different contexts: evolution, mental health, public health, personality, and problematic behaviour. Before presenting reports of the four main empirical studies in this thesis, I make the case for the importance of studying human sexuality, outline previous findings on the etiology of individual differences in sexuality, and describe the behavioural genetic principles and techniques that were used in the investigations. I also present an additional fifth paper reporting a behavioural genetic analysis of EEG power, which I undertook in order to learn twin data modelling and complex multivariate techniques. In the first empirical paper I investigated sexual orientation from an evolutionary perspective. As sexual orientation is genetically influenced, it is not known how homosexuality, which tends to lower reproductive success, is maintained in the population at a relatively high frequency. I tested the hypothesis that while genes predisposing to homosexuality reduce homosexuals’ reproductive success, they may confer some advantage for heterosexuals who carry them. Results showed that psychologically masculine females and feminine men are 1) more likely to be nonheterosexual, but 2) when they are heterosexual have more opposite-sex sexual partners. Genetic modelling revealed that both these relationships are partly due to pleiotropic genetic influences common to each trait. Further, heterosexuals with a nonheterosexual twin had more opposite-sex partners than do heterosexual twin pairs. Taken together, these results suggest that genes predisposing to homosexuality may confer a mating advantage in heterosexuals, which could contribute to the evolution and maintenance of homosexuality in the population. In the second empirical paper I investigated sexual orientation from the perspective of mental health risk. Large epidemiological studies have shown that homosexuals are at much greater risk of psychiatric disorder than the general population. This has been assumed, with some supporting evidence, to be because of the prejudice and discrimination experienced by homosexuals in a heterosexist society. Here I tested the viability of alternative explanations, using Eysenck’s Neuroticism and Psychoticism scales as markers for psychiatric vulnerability. Firstly, I tested whether apparent sexual orientation differences in psychiatric vulnerability simply mirror sex differences – for our traits, this would predict nonheterosexual males having elevated Neuroticism scores as females do, and nonheterosexual females having elevated Psychoticism scores as males do. The results contradicted this idea, with nonheterosexual men and women scoring significantly higher on both Neuroticism and Psychoticism than their heterosexual counterparts, suggesting an overall elevation of psychiatric risk in nonheterosexuals. Secondly, I used the genetically informative sample to assess the viability of explanations invoking a common cause of both nonheterosexuality and psychiatric vulnerability. We found significant genetic correlations between sexual orientation and both Neuroticism and Psychoticism, but no corresponding environmental correlations, suggesting that if there is a common cause of both nonheterosexuality and psychiatric vulnerability it is likely to have a genetic basis rather than an environmental basis. The third empirical paper investigated the etiology of risky sexual behaviour, which is relevant to public health and welfare through its role in STD transmission and unwanted pregnancies. Results showed that variation in risky sexual behaviour is due to genetic, shared environmental, and unshared environmental influences to approximately equal degrees. The genetic influences partly overlapped with genetic influences on dispositional factors, with significant genetic correlations between risky sexual behaviour and Eysenck’s Impulsivity, Extraversion, Psychoticism, and Neuroticism. This suggests that the genetic influences that shape our personality may also predispose us to risky sexual behaviour. The fourth empirical paper investigated the etiology of a strong association (r = .50) between risky sexual behaviour and adolescent misconduct. Results indicated that the association is due to overlapping genetic and environmental influences, but that in males genes are the primary source of the association whereas in females shared environment plays the greater role. These findings suggest that a general predisposition to risky behaviour may manifest in different potentially harmful ways in adolescence (misconduct) and adulthood (risky sexual behaviour), and that different processes are involved in male and female etiology. Following the empirical reports, I provide a general discussion of my research findings and the study of human sexuality more generally. After summarising the findings and their implications, I then provide a detailed description of potential limitations of the research and to what extent they qualify the conclusions drawn. I also critically discuss the absence of sexuality traits from the major models of personality, and why this and other shortcomings make the personality models inadequate from an evolutionary perspective. Finally, I suggest directions for future research in light of the research and discussion presented in this thesis.

Magister Public Health - MPH / Since the early 1980s when the first case of HIV was diagnosed, AIDS remains a serious and threatening health crisis in the world. Sub-Saharan Africa is the region most affected by the HIV/AIDS pandemic having 67 % of the 33 million people infected with HIV globally in 2007. Young people aged 15-24 account for an estimated 45% of all new HIV infections worldwide. The study aimed to assess the knowledge and attitudes on HIV/AIDS and sexual behavior among 15-19 year olds in Kenya. A descriptive, cross-sectional survey was conducted among 96 students randomly selected from five public schools in Ngong sub-district. Descriptive and bivariate analysis was conducted using Epi Info 3.3 and SPSS. The main findings indicate that a third (31/96) of respondents were sexually experienced. Knowledge level was however found to be inadequate (below 60 %) indicating a poorly informed sample on knowledge about HIV transmission and prevention. The study showed poor attitudes towards the risk to HIV as only 40 % of both males and females supported the use of condoms even when the sexual partners know each other well. Inaddition, risky sexual behaviors were reported by sexually experienced respondents where condom use in last sexual intercourse was (57 %) among males and (20 %) among females. / South Africa

Magister Public Health - MPH / Aim: The purpose of the study was to assess the knowledge of the transmission and prevention of HIV/AIDS among secondary school students in Bekwarra, Cross River State, Nigeria; to appraise the students' attitudes towards HIV/AIDS; to describe the risky sexual and other behaviours they engaged in and what factors influenced such behaviours. This study was conducted in the area to systematically examine the widely held notion that adolescents were deviating from the strict sexual mores of the Bekwarra people, thereby exposing themselves to the risk of acquiring HIV. Methods: Information was collected using a cross-sectional survey based on a 64 item questionnaire adapted from the Family Health International HIV/AIDS/STD Behavioural . Surveillance Surveys. A random sample of 381 male and female students aged 14 to 18 selected from 12 secondary schools participated in the survey. Results: The level of general awareness of HIV/AIDS was high - 56.9% of participants knew how HIV is transmitted - but their knowledge of STI symptoms was low. Only 24.7% knew at least two STI symptoms in women, while only 20.7% knew at least two STI symptoms in men. One hundred and twenty three (32.2%) students constituting 68 males (17.8%) and 55 females (14.4%) had experienced sexual intercourse. The mean age at first sexual experience was 15.06 years for males and 14.95 years for female students. There was a statistical association between age and experience of sexual intercourse (p = .024). Two thirds (65.0%) of the 123 sexually experienced students had intercourse in the last six months, and only 30 of them (24.4%) had used a condom during their last intercourse. The use of condom was most frequent (10.6%) at age 18 and least frequent (.8%) at age 14. About one quarter (26.1%) of the students had taken alcohol: 17.3% occasionally, 5.5% moderately, and 2.6% frequently. There was a statistical association between taking alcohol and age (p = .038). Over a half (56.1%) of those who had not had sexual intercourse also had not taken alcohol. In contrast, 14.2% had sexual intercourse and also took alcohol, indicating significant statistical association (p < .001).). 66.8% of the students had neither used drugs nor taken alcohol, whilst 6.8% had both used drugs and taken alcohol, indicating significant association, (p < .001)). There was a similar association between sexual intercourse and using drugs, (p = .002). Conclusions: The study revealed significant high risk sexual behaviour among adolescents in Bekwarra. The high level of risky sexual behaviour and lack of basic knowledge about STIs indicated that access to information is currently insufficient. Health and educational authorities in Bekwarra should utilize the key findings highlighted from this study to design more effective local strategies for sexual health promotion that may help to slow the spread of STIs including HIV/AIDS. Intensive child-friendly programmes for pre-teenagers organized by educators to promote postponement of the early initiation of sexual intercourse may be effective. For adolescents who are unable to control their sexual initiation, improved education on safe sexual practices, especially the use of condoms appears to be necessary. / South Africa

This study draws on cultivation analysis (Gerbner, 1969) to explore the interrelating factors concerning the role of media in young people’s consumption of alcohol at a south-eastern Nigerian university. Nigeria has the second highest alcohol consumption in Africa. Traditionally, drinking spaces were dominated by adult males for socio-cultural reasons but in contemporary Nigeria there is increasing concern that younger men and women are now also drinking harmfully. Qualitative interviews were conducted with 22 male and 9 female undergraduate students (aged 19-23 years) to explore the ways in which media consumption shapes their drinking behaviour. Whilst young people’s consumption of both local and foreign media was high and gendered, one key motivation for using alcohol was aspirational, particularly among those who consumed Hollywood films. Many of the participants who consumed Hollywood films may have learned to associate heavy consumption with high social status. Importantly, this thesis demonstrates that although local films portray alcohol in a mainly negative light, this also motivates young people to drink as they learn how to use alcohol to ameliorate anxiety or depression. Young people’s drinking patterns were found to be gendered, underscoring a resilient socio-cultural belief in which men see alcohol as good for males while women believe that it should not be confined to men. Consequently, the women employed male-gendered drinking behaviours such as heavy drinking to develop social capital. At the same time, both male and female participants discussed taking part in risky sexual behaviour but the outcomes differed for males and females, with this behaviour being more stigmatised in women. Alcohol advertising and promotion were found to be highly influential because they encourage brand preference and brand allegiance, actively facilitate change of brand, and lead to excessive consumption amongst male and female participants. Although the participants confirmed that promotional activities facilitate alcohol misuse, they argued that promotions should not be regulated because promotional prizes alleviate poverty. This study furthers the discussion on cultivation theory by demonstrating that heavy television viewing cultivates alcohol consumption among this population and it contributes to cultivation and audience research by revealing that negative portrayals can also influence young people. This study’s findings can inform educational campaigns and policy formulation in Nigeria, particularly those that tackle alcohol availability, heavy episodic drinking and risky sexual behaviour; and those that encourage media literacy and more positive and equal relationships between women and men.

Thesis (M. A. (Sociology)) -- University of Limpopo, 2017 / Contemporary moral panic about adolescents centres on their sexual behaviour, as being irresponsible, disrespectful to adults, easily addicted and indulging in unsafe sex. With this concern, parents are noted to play a vital role in supervising, monitoring, guiding, advising and addressing adolescents’ risky sexual behaviour. Adolescents are influenced by a variety of factors and institutions; hence the study explored one of the factors, ‘parents’ involvement’. The study sought to find out parents’ perceptions on involvement, what it means and how involvement can be effective. The aim of the study was to explore parents’ involvement in addressing adolescents’ sexual behaviour in Mankweng Township, Limpopo Province. The study comprised ten parents (five males and five females) who were purposely selected. Data was conducted over the course of three days, through semi-structured interviews. Thematic data analysis method was used to analyse data collected and to have final results. The findings revealed that parents are much aware of adolescents’ sexual behaviour, parents’ role and responsibility when it comes to protecting adolescents. However, a common trend was found from all parents, which was lack of understanding of parental involvement; where all participants only limited parental involvement to sexual communication and giving advice; with that they bear uncomforting belief that sexual communication will lead adolescents to sexual behaviour. Moreover, it was evident that parents have challenges to parental involvement such as peer pressure, media, fear and respect. Intervention such as parental programmes, health, religion and education; campaigns and community gatherings were noted as effective method that should the initiated to educate and improve parents’ involvement in addressing adolescents’ sexual behaviour. Keywords: Parent, adolescent, involvement, risky sexual behaviour.

<p>The aim of the study was to explore the socio-cultural influences in decision making involving sexual behaviour among adolescents in Khayelitsha, Cape Town. Cultural beliefs associated with adolescents&rsquo / decision to become sexually active were explored, as well as the social norms influences involved in adolescents&rsquo / sexual behaviour. The theoretical framework used for the study was Bronfenbrenner&rsquo / s ecological systems theory of development. The results indicated that adolescent pregnancy was perceived as unacceptable behaviour although found widespread in communities. Social influences such as peer influence, low socioeconomic status, alcohol use and lack of parental supervision were found to play a role in adolescents&rsquo / risky sexual behaviour. Cultural beliefs, cultural myths and social norms were identified as socio-cultural influences that endorsed issues such as gender disparities, which made adolescent mothers vulnerable. Findings from this study suggest that female adolescents are faced with sexual behaviour complexities.</p>

<p>The aim of the study was to explore the socio-cultural influences in decision making involving sexual behaviour among adolescents in Khayelitsha, Cape Town. Cultural beliefs associated with adolescents&rsquo / decision to become sexually active were explored, as well as the social norms influences involved in adolescents&rsquo / sexual behaviour. The theoretical framework used for the study was Bronfenbrenner&rsquo / s ecological systems theory of development. The results indicated that adolescent pregnancy was perceived as unacceptable behaviour although found widespread in communities. Social influences such as peer influence, low socioeconomic status, alcohol use and lack of parental supervision were found to play a role in adolescents&rsquo / risky sexual behaviour. Cultural beliefs, cultural myths and social norms were identified as socio-cultural influences that endorsed issues such as gender disparities, which made adolescent mothers vulnerable. Findings from this study suggest that female adolescents are faced with sexual behaviour complexities.</p>

Magister Artium (Psychology) - MA(Psych) / The aim of the study was to explore the socio-cultural influences in decision making involving sexual behaviour among adolescents in Khayelitsha, Cape Town. Cultural beliefs associated with adolescents' decision to become sexually active were explored, as well as the social norms influences involved in adolescents' sexual behaviour. The theoretical framework used for the study was Bronfenbrenner's ecological systems theory of development. The results indicated that adolescent pregnancy was perceived as unacceptable behaviour although found widespread in communities. Social influences such as peer influence, low socioeconomic status, alcohol use and lack of parental supervision were found to play a role in adolescents' risky sexual behaviour. Cultural beliefs, cultural myths and social norms were identified as socio-cultural influences that endorsed issues such as gender disparities, which made adolescent mothers vulnerable. Findings from this study suggest that female adolescents are faced with sexual behaviour complexities. / South Africa