Genetic influences on antisocial behaviour, problem substance use and schizophrenia: evidence from quantitative genetic and molecular genetic studies
John C. Gunn, Pamela J. Taylor in Forensic Psychiatry, 2014
A second assumption in twin studies is of random parental mating. If, however, assortative mating occurs, that is non-random pairing of mates based on their phenotypes, this can bias heritability estimates. To the extent that assortative mating results in increased sharing of genes in genetically unrelated spouses, this will increase the genetic resemblance of DZ twins, but not MZ twins, whose gene sharing is already 100%. In addition, assortative mating will also lead to correlated spousal environments, thus increasing the environmental similarity between parents and children. As a result of these processes, heritability estimates will be biased downward and shared environmental influences inflated (Neale and Cardon, 1992). Extensions of the traditional twin design, incorporating parental data, allow for modelling assortative mating and cultural transmission (Eaves et al., 1978; Neale and Cardon, 1992), but this is an area where adoption studies have a clear advantage (Heath et al., 1985).
Twin Studies of Human Obesity
Claude Bouchard in The Genetics of Obesity, 2020
The methods for analyzing twin data described above have important limitations. There exist a number of possible genotypic and environmental effects which the classical twin design cannot detect, but which nonetheless may result in biasing heritability estimates derived from such a design. For example, heritability estimates will be biased upward in the presence of genotype × environment correlations (such as obesity-prone individuals being reared in homes with plentiful fatty foods) and genotype × environment interactions (such as particular genotypes being more sensitive to high-fat diets). Further, special MZ twin environments (where MZ twins are treated more similarly than DZ twins) will also increase MZ intrapair correlations and, thus, result in an overestimate of heritability. In contrast, assortative mating (like marrying like) may produce spurious evidence for common environmental influences on obesity and at the same time reduce heritability estimates.
Setting the scene
Jessica Mozersky in Risky Genes, 2012
From the perspective of genetics, populations are groups who are genetically differentiated from one another because of geographical and/or cultural isolation (Burchard et al. 2003). Historically, genetic differentiation occurred largely because of geographic barriers, such as mountains, deserts or large bodies of water, which restricted mating and reproduction between people. This means that genetic differentiation often occurs between continentally separated groups, although cultural practices such as endogamy, religion and language have given rise to even further genetic subdivisions within continents (Burchard et al. 2003). This is known as ‘assortative mating’ and refers to the non-random choice of partners based on characteristics such as geographical proximity, skin colour, height or religion (Bamshad et al. 2004). Over time, these reproductive patterns result in greater genetic homogeneity than for those populations who intermarry and mate with one another (Bittles 2005). While populations are fluid and not fixed biologically, they may differ from one another genetically. Populations are never entirely reproductively closed and there will always be mating between and across groups. The mixing of two or more populations who are genetically differentiated from one another is known as ‘admixture’ (Bamshad et al. 2004). Genetic differentiation is therefore caused by physical conditions such as geography as well as factors such as religion, cultural practices and language. Isolation of populations can also be a result of discrimination, stigmatization and overt political efforts which force certain groups into isolation. In the case of Ashkenazi Jews this is particularly relevant, as they have a history of discrimination and the existence of genetic disease can become linked with their history of oppression and suffering.
Familial genetic and environmental risk profile and high blood pressure event: a prospective cohort of cardio-metabolic and genetic study
Published in Blood Pressure, 2021
Goodarz Kolifarhood, Maryam S. Daneshpour, Asiyeh Sadat Zahedi, Nasim Khosravi, Bahareh Sedaghati-Khayat, Kamran Guity, Saeid Rasekhi Dehkordi, Mahmoud Amiri Roudbar, Forough Ghanbari, Farzad Hadaegh, Fereidoun Azizi, Mahdi Akbarzadeh, Siamak Sabour
Although, ancient lifestyles, such as a salty diet and adapting a sedentary lifestyle, were reported as most frequent environmental risk factors attributed to high blood pressure in Iranian families, there was no attempts to examine familial impacts of genetic and metabolic risk factors on hypertension [19,20]. In this study, we found a positive correlation between family member’s SBP, DBP, BMI and WC, so that the correlations were different by class of relationship and it was lowest in spouses. However, our findings were in contrast to assortative mating theory [21]. Accordingly, results of previous study on Iranian families showed association between overweight and obesity in women with their spouses' risk for cardiovascular diseases regardless to the effect of the spouse’ own risk factors [22]. Nevertheless, higher correlations of blood pressure traits as well as anthropometric predictors between mother-offspring and sister-sister in our study is likely emphasised on key role of women to adapt or avoid of risky lifestyle habits, diet, cultural belief or psychosocial stressors among family members over time [23].
Human height: a model common complex trait
Published in Annals of Human Biology, 2023
Mitchell Conery, Struan F. A. Grant
An issue always worth considering when discussing any GWAS results is the effect of assortative mating. A shortcoming of Yengo et al.’s work is that they did not do so. There is an extensive literature documenting human assortative mating in general (Burgess and Wallin 1943; Price and Vandenberg 1980; Mascie-Taylor 1989; McLeod 1995; Allison et al. 1996; Du Fort et al. 1998; Maes et al. 1998; Hippisley-Cox et al. 2002; Stimpson and Peek 2005; Jurj et al. 2006; Meyler et al. 2007; Di Castelnuovo et al. 2009; Alford et al. 2011; Ask et al. 2012; Peyrot et al. 2016; Luo S 2017; Jeong and Cho 2018; Horwitz et al. 2023) and specifically, on the basis of height (Stulp et al. 2017; Torvik et al. 2022). Assortative mating can inflate SNP-based heritability estimates. For example, an analysis of ∼335,000 individuals of British ancestry found that assortative mating inflated the heritability of height by 14–23% (Border et al. 2022). However, that same study also demonstrated that sufficient sample sizes should cause the heritability estimates derived from the restricted maximum likelihood approach employed by Yengo et al. (Yang J et al. 2011, 2012) to converge to the true SNP-based heritability. It is plausible that the large sample size of this most recent GWAS is sufficient to ensure such convergence.
Circadian preference and relationship satisfaction among three types of couples
Published in Chronobiology International, 2019
Juan F. Díaz-Morales, Zaida Parra-Robledo, Cristina Escribano
For decades, psychological research has been focused on determining if there is a systematic pattern in human mate selection or assortative mating. Research on assortative mating has typically been framed in terms of similarity (or positive assortment) versus complementarity (or negative assortment) of partners’ characteristics. Overall, there is consistent evidence for similarity but very little evidence for differences. The degree of similarity observed depends on the particular individual-difference domain studied, with romantic partners showing strong similarity in age, political and religious attitudes; moderate similarity in education, general intelligence, and values; and little or no similarity in personality characteristics (Rammstedt and Schupp 2008).
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