Fertility Outcomes, Heritability and Genomic Associations of In-Group Preference and In-Group Marriage

Using data from the Midlife Development in the USA (MIDUS) sample (3070 men and 3182 women) and the Wisconsin Longitudinal Study (WLS; 2240 men and 2346 women), we aimed to investigate whether religious, ethnic and racial in-group preferences as well as religious homogamy are associated with reproductive outcome in terms of number of children. Using data from the MIDUS twin sample, we further estimated the inherited genetic component of in-group attitudes. Additionally, we analyzed the association of ∼50 polygenic scores (PGSs) recently published for the WLS study and in-group attitudes as an indicator of potential pleiotropic effects. We found in both samples that, with one exception, religious though not other in-group attitudes are associated with a higher reproductive outcome. Also, religious homogamy is associated with higher average number of children. The inherited component of all in-group attitudes ranges from ∼21% to 45% (MIDUS twin sample). PGSs associated with religious behavior are significantly positively associated with religious in-group attitudes as well as family attitudes. Further associations are found with PGS on life satisfaction (work) and, negatively, with PGS for any sort of addiction (smoking, alcohol and cannabis use), indicating pleiotropy. We conclude that the positive association between religious in-group attitudes as well as religious homogamy and reproductive outcome may indicate selective forces on religious in-group behavior. As all investigated in-group attitudes, however, have a substantial inherited component, we further speculate that potential previous reproductive benefits of racial and ethnic in-group preferences, if they ever existed, might have been substituted by religious in-group preferences.

The Australian Twins Economic Preferences Survey

This article describes the Australian Twins Economic Preferences Survey (ATEPS). The data set comprises a wide variety of preference and behavioral measures (risk aversion, impatience, ambiguity aversion, trust, confidence) elicited using incentivized decision tasks. One-thousand one-hundred twenty Australian adult twins (560 pairs) completed the survey, making it one of the largest data sets containing incentivized preference measures of twins. As the survey was conducted during the COVID-19 pandemic, we also collected information on experiences related to the pandemic, along with a variety of questions on political attitudes and mental wellbeing. We hope that ATEPS can make a valuable contribution to social science and genetics research.

Twins with Craniosynostosis: An Unidentified Variant/Twin Research: Kangaroo Care for Premature Twins; Developmental Delay in MZ Twins; Osteosarcoma in One Identical Twin; Controversies in Twin Pregnancy Management/Media Reports: Twin and Triplet Olympians; Twin’s Rescue from a Crocodile; Twin Pandas in Japan; Twin Surrogacy; Identical Twins in Pennsylvania

Craniosynostosis involves the early closure of one or more joints connecting the bones of an infant’s skull. A case of young monozygotic (MZ) male twins with an unidentified variant of this condition is described, followed by a summary of relevant published reports. This overview is followed by descriptions of a kangaroo care program for premature twins, developmental delay in an MZ twin pair, osteosarcoma in one MZ twin and controversial issues in the management of multiple pregnancies. Media reports of twin and triplet Olympic athletes, a twin’s rescue from a crocodile, the birth of twin pandas in Japan, a case of twin surrogacy and the birth of identical triplets are also presented.

Large Hemoglobin Differences at Birth in Monochorionic Twins with a Placental Chorangioma and Delayed Cord Clamping

We report a case of a monochorionic diamniotic twin with an uncomplicated pregnancy, but with an unexpected large intertwin hemoglobin (Hb) difference at birth. Twin 1 was delivered vaginally and had an uneventful neonatal course. The umbilical cord of Twin 1 was clamped approximately 5 min after birth. After the birth of Twin 1, Twin 2 developed severe bradycardia and showed limited cardiac output on ultrasound, for which an emergency cesarean section was performed. A full blood count revealed an Hb of 20.1 g/dL for Twin 1 and 10.2 g/dL for Twin 2 (intertwin difference 9.9 g/dL). Reticulocyte counts were similar, 40‰ and 38‰, respectively. Placental examination revealed 10 vascular anastomoses, including one arterio-arterial anastomosis with a diameter of 1.4 mm. Additionally, a large chorangioma was present on the placental surface of Twin 2. There was no color difference on the maternal side of the placenta. Based on the reticulocyte count ratio and the placental characteristics, twin anemia polycythemia sequence was ruled out as the cause of the large intertwin Hb difference. In this report, we discuss the various potential causes that could explain the large intertwin Hb difference including the role of delayed cord clamping in Twin 1, and the role of a large chorangioma, which may have attracted blood from the fetal circulation of Twin 2.

DNA Methylation of TXNIP Independently Associated with Inflammation and Diabetes Mellitus in Twins

Thioredoxin-interacting protein (TXNIP) plays a key role in diabetes development and prognosis through its role in pancreatic β-cell dysfunction and death as well as in upregulating the inflammatory response in hyperglycemia. DNA methylation (DNAm) of TXNIP (TXNIP-cg19693031) is associated with the prevalence and incidence of type 2 diabetes (T2D); however, its role in inflammation and its relationship with T2D remain unclear. We aimed to investigate the epigenetic associations of TXNIP-cg19693031 with a panel of inflammatory biomarkers and to examine whether these inflammatory biomarkers modify the association between TXNIP-cg19693031 methylation and diabetes in 218 middle-aged male twins from the Emory Twin Study. We confirmed the association of TXNIP-cg19693031 DNAm with T2D, as well as with HbA1c, insulin and fasting glucose. We found that hypomethylation at TXNIP-cg19693031 is strongly associated with both type 2 diabetes and higher levels of inflammatory biomarkers (VCAM-1, ICAM-1, MMP-2, sRAGE and P-selectin); however, the relationship between TXNIP-cg19693031 and T2D is independent of the levels of these inflammatory biomarkers. Our results suggest that DNA methylation of TXNIP is linked with multiple biological processes, through which the TXNIP may have broad influence on chronic disease risk.

Fetal Hemodynamic Responses to Arterial Occlusion of Acardiac Twins

The objective of this study was to comprehensively assess fetal hemodynamic adaptions to occlusive procedures. Twin pregnancies complicated with acardiac twin and hydrops fetalis of the pump twin were recruited. The occlusive procedures — either alcoholization, radiofrequency ablation, coil embolization or occlusive glue — were performed under ultrasound guidance. Various hemodynamic parameters were assessed before, shortly after, then every 6 h for 48 h and 2−4 weeks after the procedures. Seven pregnancies were recruited. The median (range) gestational age of intervention was 21 (17−26) weeks of gestation. Before the procedures, all cases showed normal cardiac function. Just after the procedures, all cases showed an increase in Tei index and isovolumic relaxation time but returned to preocclusion levels within 6−48 h, except for two cases that were persistently high. Increased preload and poor shortening fraction were observed in two cases, leading to heart failure, with one recovery and one death in utero. Five out of the seven cases got through the critical period with a gradual return to normal hemodynamics, ending with the disappearance of hydrops and successful outcomes. It was concluded that the occlusive procedure could aggravate the overworked heart, leading to heart failure. Preocclusion preload index and Tei index may predict risk of heart failure due to the occlusion. This small series strongly suggests that the occlusion should be performed before the deterioration of cardiac function.

Predicting Alcohol Dependence Symptoms by Young Adulthood: A Co-Twin Comparisons Study

Co-twin comparisons address familial confounding by controlling for genetic and environmental influences that twin siblings share. We applied the co-twin comparison design to investigate associations of adolescent factors with alcohol dependence (AD) symptoms. Participants were 1286 individuals (581 complete twin pairs; 42% monozygotic; and 54% female) from the FinnTwin12 study. Predictors included adolescent academic achievement, substance use, externalizing problems, internalizing problems, executive functioning, peer environment, physical health, relationship with parents, alcohol expectancies, life events, and pubertal development. The outcome was lifetime AD clinical criterion count, as measured in young adulthood. We examined associations of each adolescent domain with AD symptoms in individual-level and co-twin comparison analyses. In individual-level analyses, adolescents with higher levels of substance use, teacher-reported externalizing problems at age 12, externalizing problems at age 14, self- and co-twin-reported internalizing problems, peer deviance, and perceived difficulty of life events reported more symptoms of AD in young adulthood (ps < .044). Conversely, individuals with higher academic achievement, social adjustment, self-rated health, and parent–child relationship quality met fewer AD clinical criteria (ps < .024). Associations between adolescent substance use, teacher-reported externalizing problems, co-twin-reported internalizing problems, peer deviance, self-rated health, and AD symptoms were of a similar magnitude in co-twin comparisons. We replicated many well-known adolescent correlates of later alcohol problems, including academic achievement, substance use, externalizing and internalizing problems, self-rated health, and features of the peer environment and parent–child relationship. Furthermore, we demonstrate the utility of co-twin comparisons for understanding pathways to AD. Effect sizes corresponding to the associations between adolescent substance use, teacher-reported externalizing problems, co-twin-reported internalizing problems, peer deviance, and self-rated health were not significantly attenuated (p value threshold = .05) after controlling for genetic and environmental influences that twin siblings share, highlighting these factors as candidates for further research.