Opposite-sex and same-sex twin studies of physiological, cognitive and behavioral traits

Linda Juel Ahrenfeldt; Kaare Christensen; Nancy L Segal; Yoon-Mi Hur

doi:10.1016/j.neubiorev.2019.11.004

Opposite-sex and same-sex twin studies of physiological, cognitive and behavioral traits

Neurosci Biobehav Rev. 2020 Jan:108:322-340. doi: 10.1016/j.neubiorev.2019.11.004. Epub 2019 Nov 8.

Authors

Linda Juel Ahrenfeldt¹, Kaare Christensen², Nancy L Segal³, Yoon-Mi Hur⁴

Affiliations

¹ Unit of Epidemiology, Biostatistics and Biodemography, Department of Public Health, University of Southern Denmark, 5000, Odense, Denmark; The Danish Twin Registry, Department of Public Health, University of Southern Denmark, 5000, Odense, Denmark.
² Unit of Epidemiology, Biostatistics and Biodemography, Department of Public Health, University of Southern Denmark, 5000, Odense, Denmark; The Danish Twin Registry, Department of Public Health, University of Southern Denmark, 5000, Odense, Denmark; Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, 5000, Odense, Denmark; Department of Clinical Genetics, Odense University Hospital, 5000 Odense, Denmark.
³ Department of Psychology, California State University, 800 N. State College Blvd., Fullerton, CA, 92834, USA.
⁴ Education Research Institute, Department of Education, Mokpo National University, Jeonnam, South Korea. Electronic address: ymhur@mokpo.ac.kr.

Abstract

A scientific interest in opposite-sex (OS) twins comes from animal studies showing hormone transfer between fetuses in utero. A parallel effect in humans may occur, especially for OS females who may be exposed to androgens, in particular testosterone, from the male co-twin. Conversely, OS males may be exposed to lower levels of prenatal testosterone than do same-sex (SS) males. In this special issue, we reviewed published studies investigating potential differences between OS and SS twins in physiological, cognitive and behavioral traits focusing on the Twin Testosterone Transfer (TTT) hypothesis. Sixty articles fulfilled the eligibility criteria including 23 studies published since the review by Tapp et al. (2011). In general, studies of cognition are conflicting, but it is the phenotype for which most support for the TTT hypothesis is found. Less consistent evidence has been found regarding physiological and behavioral traits. We hope that this special issue will stimulate a discussion about how an investigation of the TTT hypothesis should continue in future research.

Keywords: Behavior; Cognition; Masculinization; Opposite-sex; Physiology; Same-sex; Sex differences; Testosterone; Twins.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Review
Twin Study

MeSH terms

Animals
Female
Human Development / physiology*
Humans
Male
Personality / physiology*
Pregnancy
Pregnancy, Twin / metabolism*
Sex Characteristics*
Social Behavior*
Testosterone / metabolism*
Twins*

Substances

Testosterone

Abstract

Publication types

MeSH terms

Substances

Grants and funding