Adoption Research and Twin Studies Overview

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Questions and Answers

What are cohort studies, particularly in the context of adoption research?

Cohort studies are longitudinal studies that follow research participants over time, specifically focusing on families who have adopted a child from birth.

What is the primary structural feature of the adoption cohort data mentioned in the Colorado Adoption Project?

The Colorado Adoption Project involves multiple families, including adoptive mothers, fathers, and biological parents, along with a control group to provide comparative data.

What key finding is noted about the contact between adoptive and birth families in the studies mentioned?

Both studies report minimal selective placement and minimal contact between adoptive and birth families.

How do the Colorado Adoption Project and the Early Growth and Development Study ensure methodological rigor?

Both studies control for variables, such as contact between adoptive and birth families, as measured covariates in their analyses. Signup and view all the answers

What is the mean age of placement for children in the Colorado Adoption Project?

The mean age of placement for children in the Colorado Adoption Project is 29 days. Signup and view all the answers

What was the main finding of the Minnesota Study of Twins Reared Apart regarding personality similarities?

Twins reared apart have about the same chance of being similar in personality, interests, and attitudes as those reared together. Signup and view all the answers

What ethical concerns have been raised about separating twins for research purposes?

It is generally considered unethical to separate twins for research due to the potential psychological impact and the violation of familial bonds. Signup and view all the answers

In what ways did the Jim twins exemplify the findings of the Minnesota Study?

The Jim twins demonstrated remarkable similarities in life choices and preferences, despite being raised apart, such as similar marriages and pet names. Signup and view all the answers

What was the focus of the Fullerton Study of Chinese Twins reared apart?

The study examined twins accidentally switched or misplaced at birth, contributing to understanding of nature versus nurture. Signup and view all the answers

How did the conclusion of Bouchard et al. differ from the earlier understandings of the role of environment in twin studies?

Bouchard et al. concluded that the environment differentiates twins, contrary to the belief that it makes them alike. Signup and view all the answers

What was the significance of the 1979 Minnesota Study in the context of twin studies?

It was one of the largest studies investigating twins raised apart, establishing important findings in psychology and genetics. Signup and view all the answers

What were the results of the study led by Segal et al. in 2018 involving mismatched twins?

The study found similarities in behavior and personality among the mismatched twins, supporting earlier findings on genetic influence. Signup and view all the answers

Why is it increasingly deemed unethical to conduct studies that separate twins?

Such practices are seen as violating ethical standards regarding human rights and psychological harm to individuals. Signup and view all the answers

What was the main finding of Burks' 1928 study regarding heredity and intelligence?

Burks' study concluded that intelligence is largely determined by heredity, suggesting that environment cannot significantly influence an individual's IQ. Signup and view all the answers

What significant critique was raised against Burks' conclusions in later studies?

Rajan (1983) critiqued Burks' conclusions, suggesting that the interplay between heredity and environment was not adequately considered. Signup and view all the answers

In what year did Skodak and Skeels conduct their adoption study, and what was its unique aspect?

Skodak and Skeels conducted their adoption study in 1949, marking it as the first full adoption study that included both birth and adoptive parents. Signup and view all the answers

What impact did improved home environments have on the IQ of adopted children compared to their birth parents, according to Skodak and Skeels?

Adopted children exhibited higher IQs than their birth parents, indicating that a better home environment positively influenced their intelligence. Signup and view all the answers

What issue related to 'selective placement' was highlighted in the Skodak and Skeels study?

'Selective placement' raised concerns that children were often placed in adoptive homes similar to their birth families' socioeconomic status, affecting study results. Signup and view all the answers

Why is it important for adoption studies to assume no selective placement?

Assuming no selective placement is crucial to isolate the effects of heredity from environment in determining intelligence. Signup and view all the answers

What age range did Burks' 1928 study focus on for its participants?

Burks' study focused on children aged 5 to 14 years. Signup and view all the answers

What general conclusion can be drawn from both Burks' and Skodak and Skeels' studies regarding intelligence?

Both studies underscore the complex relationship between heredity and environment in influencing intelligence. Signup and view all the answers

What is the significance of a national birth registry?

It serves as an important data source for research, providing information on everyone born in the country. Signup and view all the answers

How do Scandinavian countries utilize national registry data?

They create population cohorts to track groups of interest over time through administrative records. Signup and view all the answers

What role does a unique personal identification number play in national registries?

It links individuals' administrative data across national public registries. Signup and view all the answers

What types of data can be accessed from Scandinavian registry studies?

Data on health, education, housing, childbirth, and even criminal records can be accessed. Signup and view all the answers

What effect does being raised in adoptive homes have on the risk of drug abuse?

Siblings raised in adoptive homes had a substantially reduced risk for drug abuse. Signup and view all the answers

How are sibling pairs with a high genetic risk for drug abuse studied?

They are exposed to different rearing environments to analyze their behavioral outcomes. Signup and view all the answers

What does Administrative Data Research UK provide to researchers?

It grants access to the UK’s public sector data, enhancing research capabilities. Signup and view all the answers

What types of families can registry data help researchers identify?

It can help find all types of adoptive families and those involved in family courts. Signup and view all the answers

What was the primary finding regarding adoptees and their biological versus adoptive parents in terms of divorce history?

Adoptees resembled their biological parents rather than their adoptive parents in their history of divorce. Signup and view all the answers

How does the history of divorce among adoptive siblings compare to that of biological siblings based on the study?

Adoptees resembled their biological siblings, not adoptive siblings, in their history of divorce. Signup and view all the answers

What heritability estimate was found for divorce across generations?

The heritability estimate for divorce across generations was 0.13. Signup and view all the answers

What covariates were controlled in the study when assessing the impacts of genetics and environment on divorce?

The study controlled for parent education, parent externalizing behaviors, and offspring year of birth. Signup and view all the answers

In which population were the findings of the study primarily gathered?

The findings were primarily gathered from Swedish and Finnish registry data. Signup and view all the answers

How did the history of divorce differ between offspring living with their biological vs. adoptive parents?

Offspring resembled their not-lived-with fathers and their lived-with mothers in their history of divorce. Signup and view all the answers

What external factors were included as part of parent externalizing behaviors in the study?

External factors included alcohol use disorder, drug abuse, and criminal behavior. Signup and view all the answers

What is the sample size of the adoptees in the study, and why is this number significant?

The sample size of the adoptees was 19,715, which is significant for drawing reliable conclusions. Signup and view all the answers

What is the significance of measuring postnatal stress in relation to a child's antisocial behavior?

Postnatal stress is associated with the child's antisocial behavior, indicating that environmental factors, alongside genetic links, play a crucial role in shaping behavior. Signup and view all the answers

Explain why associations between stress and child behavior may differ in related versus unrelated mother-child pairs.

Associations in related pairs suggest genetic links, while equivalent associations in unrelated pairs indicate environmental influences. Signup and view all the answers

List at least three covariates that were controlled for in the study of child behavior.

Child age, child gender, and family social class are three covariates controlled for in the study. Signup and view all the answers

What type of data does a registry store, and how is it used in public services?

A registry stores uniform administrative data and is used in public services to monitor, improve performance, and carry out transactions. Signup and view all the answers

Define the term 'national registry' and give an example.

A national registry is a collection of records about individuals maintained by a nation, such as a national health registry; Signup and view all the answers

Discuss how antenatal health impacts maternal and child wellbeing.

Antenatal health influences maternal anxiety and depression, which can subsequently affect the child's development and behavioral outcomes. Signup and view all the answers

Why might maternal age at childbirth be considered an important covariate?

Maternal age at childbirth can affect both the mother's health and the child's developmental outcomes, making it a critical factor in studies. Signup and view all the answers

How does registry data facilitate health and social services?

Registry data provides essential information that helps organizations track services, monitor public health, and ensure effective delivery of interventions. Signup and view all the answers

Study Notes

Quantitative Genetics 3: Adoption Studies

This course covers adoption studies in quantitative genetics
The instructor is Dr. Tom McAdams, MSc DevPP
The course is part of a larger module titled "Nature Nurture 1"

Learning Objectives

Students will understand the logic behind using adoption studies
Students will learn about the strengths and limitations of different adoption study approaches
Key approaches include using adoptive parents and children, biological parents and children, children from IVF, siblings reared apart, and unrelated siblings reared together
Students will learn what each approach can and cannot tell us about the influence of genetics and/or environments on child development

What Influences Child Development?

Adoption studies aim to disentangle the interwoven effects of genetics and environment on child development
The factors influencing child development are presented visually as interacting variables (e.g., parental influence, genetics, environment)

The Basis of Adoption Designs

Adoption designs are a type of natural experiment used to study the interaction of genetics and environment
The procedures rely on the separation of gene and environment influences to better understand their respective effects

Control Variables in Adoption Studies

A control variable is an element held constant throughout an experiment or analysis to assess the causal relationship between other variables
Control variables help control for confounding factors in adoption studies

Parents Who Used an Egg and Sperm Donor for IVF

This approach controls for genetic and environmental factors in the study of child development

Parents Who's Biological Child is Born Via Surrogacy

This approach controls variables related to surrogate births

Parents Who Gave Their Child for Adoption at Birth

This approach controls for genetic and environmental factors related to the adoption process

Identical Twins Raised Separately from Birth

This design avoids the necessity for parents in the adoption study which helps researchers isolate genetic influences more precisely

Biological Siblings Raised Separately from Birth

This approach focuses on sibling pairs to observe shared environmental and genetic influences

Unrelated Siblings Raised Together from Birth

Studying unrelated siblings reared together helps isolate the role of shared environment

Summary of Adoption Studies

Families of biological parents and children share both genes and environment
Genetic relatives share genetic material but not environments
Environmental relatives share environments but not genetic material

Early Adoption Studies

Early studies of intelligence (IQ) examined foster children and their resemblance to their biological parents and adoptive parents
Early studies on twins highlight the use of twins reared apart as a tool for determining the heritability of different traits

Early Adoption Studies (IQ Study Example)

The study of IQ (e.g., Burks 1928) was conducted with 214 foster children and 105 control children
These studies measured intelligence in both generations and assessed the combination of nature and nurture influences using measures from both foster and biological families
Later, the conclusions of these IQ studies were critiqued

Selective Placement

Ideally, in adoption studies, there should be no systematic bias in placement to ensure that resemblance between participants is not due to preferential placement practices

Bigger, Longitudinal, Non-Twin Adoption Designs

These studies focus on larger, longitudinal samples that follow adopted children for extended periods to assess the relationships between multiple factors

Adoption Cohort Data

Cohort studies are longitudinal approaches that follow research participants over time (often many years)
Adoption cohort studies follow families who have adopted a child from birth by collecting data on the child, adoptive parents, and birth parents over a period of time

Colorado Adoption Project (CAP) and Early Growth and Development Study (EGDS)

These are specific large-scale studies of adoption focusing on specific traits (e.g., intelligence, body mass index)
This data set provides information about characteristics that are correlated between adoptive and biological family members

Early Growth and Development Study (EGDS) Methods

Analysis often focuses on longitudinal data using panel data (repeated measurements over time) in combination with structural equation models to analyze the influence of multiple factors (genetics, environment) on children's development

Limitations of Adoption Studies

Adoption studies can be resource-intensive, requiring considerable time and financial resources
The sample size may be small leading to limited generalizability of findings to larger populations
The adopted children's upbringing can vary in many ways, and any effects of the rearing family on the childs phenotype must be carefully ascertained
Selective placement into homes could bias the results (e.g., socioeconomic status)
The time required for the participants to mature makes such studies very challenging
Researchers need access to data about birth parents and openness to contact between the participants, therefore, there is difficulty in controlling for all possible influences across cohorts
Parents who have children via IVF and or through surrogacy methods require careful consideration for possible confounding variables
The studies have been accused of being biased toward Caucasian researchers studying Caucasian participants, creating concerns about the generalizability to other populations

Using Pre-Existing Datasets for Adoption Designs

Researchers can use existing datasets for studying the results of adoption with the help of registries
National registries offer access to detailed information

Swedish Registry Data

Swedish registry data combines census data with health and criminal justice records to examine factors (e.g., divorce, drug abuse) across adopted persons, birth parents, and adoptive parents

Finnish Registry Data

In Finnish adoption studies, longitudinal data was combined with clinical observations and interviews to assess traits
This method provides more detail about the participants' lives

UK Biobank Genomic Data

This dataset integrates genomic data with results of adoption studies to obtain more extensive data on multiple generations, creating larger sample sizes

Further Exercise and Summary

The exercises are to illustrate the principles used in data interpretative analysis to establish the relationship between nature and nurture
Adoption designs provide an important tool for understanding how much a child's development is influenced by their biological parents, versus their adoptive parents

Bibliography

This section provides bibliographic citations for articles and studies used in the presentation

Studying That Suits You

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Description

This quiz explores key concepts in adoption research and twin studies, focusing on cohort studies like the Colorado Adoption Project and the Minnesota Study of Twins Reared Apart. It highlights structural features of adoption cohort data, findings on family contact, and ethical considerations in research methodology. Engage with important studies and their implications on understanding personality and environment.