Family and attitudes concerning sex and reproduction


This project investigates whether individuals' gendered fitness interests (GFI) - the fitness stake each participant has in their feminine and masculine kin - explain significant variations in social, political and cultural attitudes, beyond the effects of individual sex alone. Participants will anonymously complete a survey including demographics, family structure and questions concerning attitudes to family and gender roles plus a small number of questions about contemporary events. We look to estimate the magnitude of any effects of GIF on these attitudes.

Research Questions / Hypotheses

Do individuals’ gendered fitness interests (GFI) predict variations in socioeconomic, cultural and political attitudes?


165 REP participants completed the study. Students who did not finish the study were excluded.


Participants will anonymously    complete a survey about themselves and their demographic and socioeconomic background (PART 1), and about the structure of their families (PART 2). They will then answer a battery of standard questions concerning attitudes to sex, reproduction and gender roles plus a small number of questions about contemporary events (PART 3). We look to estimate the magnitude of any effects of GFI on these attitudes.


To understand the effect of GFI on these attitudes, we calculate a GFI coefficient for each person. To do so, we determine each relatives residual reproductive value using their sex and age. We then sum these RRV scores across kin groups, multiplying this by genetic relatedness coefficients. Each person who participated is left with a coefficient indicating the degree to which they can expect future reproductive fitness to derive from male versus female relatives.    Our analysis plan is to use linear regression and regress each outcome variable onto GFI and relevant covariates, to determine if GFI predicts attitudes toward politics.


Views concerning abortion, contraception, the importance of men being masculine and women feminine, and sexual autonomy of women tend to polarize along the progressive-conservative political axis (Eysenck 1975, Feather 1977, Sidanius and Ekehammar 1980, Ekehammar and Sidanius 1982, Devaus and Mcallister 1989, Eagly et al. 2003). This axis is also associated with variation in attitudes to economic issues such as inequality,    wealth redistribution, spending on public goods such as health care and education, and military spending (Pratto et al. 1994, Sidanius et al. 1994).    Most discussion of variation in political attitudes focuses on cultural and economic factors. The strikingly high correlations between parents and offspring in moral and political views, for example, were thought to be due to upbringing, habitus (locally shared values and dispositions), and shared economic interests (Eagly et al. 2004, Eagly and Diekman 2006, Diekman and Schneider 2010). But genetic inheritance also appears to play a part. A    number of high-profile research groups are beginning to dissect the role of biology in political and moral opinion formation.    Experimental research shows that people very quickly discern and adopt the moral position that suits their selfinterest in economic games. Ideological battles (e.g., surrounding feminism and anti-feminist backlash) constitute tussles in which individuals project ideas that serve their own evolutionary interests at the expense of the other sex or of same-sex competitors.    Political beliefs concerning sex, reproduction and the distribution of resources tend to show sex differences (e.g. Twenge 1997, Manza and Brooks 1998, Eagly et al. 2004, Eagly and Diekman 2006, Bell et al. 2018). And yet these differences are often surprisingly small, with some members of one sex holding strong opinions antithetic to the interest of many of their own sex (e.g. women who hold “pro-life” beliefs) (Saad 2012). Several factors other than sex clearly shape ideological positions. These include religion, education and income.    I propose here to test the importance of a largely overlooked factor that may shape political and ideological beliefs: the fact that Individuals differ in how much of their future fitness is likely to come through females relative to males. Evolutionary kin selection theory (Hamilton 1964a, b) predicts that behaviour should transcend selfinterest and extend to the interests of genetic relatives. This theoretic insight has revolutionised the study of animal behaviour over the last 50 years, and it has had some modest success in explaining human behaviours including nepotism and variation in parental care (Daly and Wilson 2005).    There is some evidence that the sexes of immediate descendant kin can change attitudes to ideologically polarising issues such as abortion and income redistribution. Attitudes to abortion are associated with the number of female kin a person has in the 15-50 age group “at risk” of unwanted pregnancy. Economists have shown that parents of daughters favour gender equity policies more than parents of sons do and US congressmen with daughters vote more progressively regarding reproductive rights, working families and education. Parents of daughters vote more for left-wing parties than do parents of sons, and the birth of a daughter can cause a swing    to the political left, whereas the arrival of a son can do the opposite.    The research results will be submitted to academic journals for publication and will be included in presentations for academic conferences. Participant confidentiality will be maintained in reports and publications as no identifying information will be provided in these.