3.1 Unit Overview

Andrea Gretchev, RN, MN, CCNE

3.1 Unit Overview

Learning Objectives

Explore whether the nature–nurture debate is still relevant.
Examine the research designs that can be used to study nature–nurture questions.
Define genetic determinism and identify how it relates to epigenetics.
Review the developmental origins of health and disease and the impacts on long-term health outcomes.
Establish how the exposome can influence gene expression.
Determine the relationship between the social determinants of health and genetics and identify policy implications.
Explore how adverse early childhood experiences or toxic stress can lead to adverse health outcomes later in life.
Establish the significance of epigenetics to practice.

Outline

Topics covered in this chapter include:

Nature vs nurture
Epigenetics
Developmental origins of health and disease
The exposome
Adverse early childhood experiences
Epigenetics in practice

Competencies Nurses will Develop in this Chapter

ANA (2023):

Nursing assessment: Applying/integrating genomic knowledge:

Collects, reviews, and updates personal and family health history to include any genomic testing and environmental and other risk factors.

Conducts health and physical assessments that incorporate knowledge about known or potential environmental, genomic, and other risk factors (e.g., behavioral, lifestyle).

Provision of education, care, and support:

Uses health promotion and disease prevention practices that consider genomic influences as well as personal and environmental risk factors.

NHS (2023):

Identify individuals who might benefit from genomic services and/or information as part of assessing needs and planning care:

recognizing the importance of family history in assessing predisposition to a genetic condition;

Demonstrate a knowledge and understanding of genomics in human development, variation and health to underpin effective practice:

relating it to the maintenance of health and manifestation of conditions; and
relating it to the prevention and management of a genomic condition or response to treatment.

Provide ongoing nursing care and support to patients, carers, families and communities with genomic healthcare needs:

being responsive to changing needs through the life-stages and during periods of uncertainty.

Key terminology

Adverse Childhood Experiences (ACEs)

ACEs are potentially traumatic events that occur in childhood (0-17 years) and can include, but are not limited to experiencing violence, abuse, or neglect, witnessing violence in the home or community, having a family member attempt of die by suicide, growing up with substance use or mental health issues in the home, parental separation or divorce, or having family members in prison. ACEs can have a lasting effect on health and well-being well into adulthood (CDC, 2024).

Adoption study

A behavior genetic research method that involves comparison of adopted children to their adoptive and biological parents (Tuckheimer, 2024).

Behavioral genetics

The empirical science of how genes and environments combine to generate behavior (Tuckheimer, 2024).

Critical Periods

Periods of development where an organism is susceptible to the influence of environmental exposures on organ development and gene expression (OTIS, 2023).

Deletion

A deletion, as related to genomics, is a type of mutation that involves the loss of one or more nucleotides from a segment of DNA. A deletion can involve the loss of any number of nucleotides, from a single nucleotide to an entire piece of a chromosome.

Developmental Programming

The process where environmental exposures and experiences during critical developmental periods influence gene expression and shape the structure, function, and long-term health outcomes including growth, metabolism, and neurodevelopment of an individual (Padmanabhan et al., 2016).

Diagnostic Odyssey

The often long period of time it can take for a patient to receive a diagnosis for their condition (Genomics Education Programme, 2021).

Environmental Factors

Environmental factors, as related to genetics, refers to exposures to substances (such as pesticides or industrial waste) where we live or work, behaviors (such as smoking or poor diet) that can increase an individual’s risk of disease or stressful situations (such as racism). Genetic studies often take environmental factors into consideration, as these exposures can increase an individual’s risk of genetic damage or disease.

Epigenetics

Epigenetics (also sometimes called epigenomics) is a field of study focused on changes in DNA that do not involve alterations to the underlying sequence. The DNA letters and the proteins that interact with DNA can have chemical modifications that change the degrees to which genes are turned on and off. Certain epigenetic modifications may be passed on from parent cell to daughter cell during cell division or from one generation to the next. The collection of all epigenetic changes in a genome is called an epigenome.

Exposome

The measure of all the exposures of an individual in a lifetime and how those exposures relate to health (CDC, 2022).

Fraternal Twins

Fraternal twins (also called dizygotic twins) result from the fertilization of two separate eggs with two different sperm during the same pregnancy. Fraternal twins may not have the same sex or appearance. They share half their genomes, just like any other siblings. In contrast, identical twins (or monozygotic twins) result from the fertilization of a single egg by a single sperm, with the fertilized egg then splitting into two. As a result, identical twins share the same genomes and are always the same sex.

Gene Expression

Gene expression is the process by which the information encoded in a gene is used to either make RNA molecules that code for proteins or to make non-coding RNA molecules that serve other functions. Gene expression acts as an “on/off switch” to control when and where RNA molecules and proteins are made and as a “volume control” to determine how much of those products are made. The process of gene expression is carefully regulated, changing substantially under different conditions. The RNA and protein products of many genes serve to regulate the expression of other genes.

Gene Regulation

Gene regulation is the process used to control the timing, location and amount in which genes are expressed. The process can be complicated and is carried out by a variety of mechanisms, including through regulatory proteins and chemical modification of DNA. Gene regulation is key to the ability of an organism to respond to environmental changes.

Gene–Environment Interaction

Gene–environment interaction refers to the interplay of genes (and, more broadly, genome function) and the physical and social environment. These interactions influence the expression of phenotypes. For example, most human traits and diseases are influenced by how one or more genes interact in complex ways with environmental factors, such as chemicals in the air or water, nutrition, ultraviolet radiation from the sun and social context.

Genetic Determination

Is the belief that one’s biological/genetic nature if fixed and is the sole determinant of phenotype (Harden, 2023).

Genetic Imprinting

Genomic imprinting is the process by which only one copy of a gene in an individual (either from their mother or their father) is expressed, while the other copy is suppressed. Unlike genomic mutations that can affect the ability of inherited genes to be expressed, genomic imprinting does not affect the DNA sequence itself. Instead, gene expression is silenced by the epigenetic addition of chemical tags to the DNA during egg or sperm formation. Epigenetic tags on imprinted genes usually stay in place for the life of the individual.

Heritability Coefficient

An easily misinterpreted statistical construct that purports to measure the role of genetics in the explanation of differences among individuals (Tuckheimer, 2024).

Identical Twins

Identical twins (also called monozygotic twins) result from the fertilization of a single egg by a single sperm, with the fertilized egg then splitting into two. Identical twins share the same genomes and are nearly always the same sex. In contrast, fraternal (dizygotic) twins result from the fertilization of two separate eggs with two different sperm during the same pregnancy. Like most other siblings, fraternal twins share half of their genomes. The sex of one fraternal twin has no relation to the sex of the other and they may not have similar appearances.

Neuronal (or synaptic) Pruning

Synaptic pruning is a process that occurs in the brain between early childhood and adulthood where the brain eliminates extra synapses that are not being used (Gill, 2018).

Quantitative Genetics

Scientific and mathematical methods for inferring genetic and environmental processes based on the degree of genetic and environmental similarity among organisms (Tuckheimer, 2024).

Rare Disease

A disease that affects less than 1 in 2,000 of the general population (EU definition). In the UK, approximately 3.5 million people will be affected by a rare disease at some point in their life (Rare Disease UK) (Genomics Education Programme, 2022).

Twin Studies

A behavior genetic research method that involves comparison of the similarity of identical (monozygotic; MZ) and fraternal (dizygotic; DZ) twins (Tuckheimer, 2024).

Uniparental Disomy

Uniparental disomy (UPD) occurs when a person receives two copies of a chromosome, or part of a chromosome, from one parent and no copies from the other parent. UPD can occur as a random event during the formation of egg or sperm cells, or it may happen during early fetal development (NIH: National Library of Medicine, n.d.).

Attribution & References

Except where otherwise noted, this page is adapted from the following sources:

- Talking Glossary of Genomic and Genetic Terms, Courtesy of: National Human Genome Research institute (NGHRI), Public Domain with attribution.
- Definitions for Rare Disease & Diagnostic Odessey from Genomics Glossary by Genomics Education Programme, CC BY-NC

References

American Nurses Association (ANA). (2023). Essentials of genomic nursing: Competencies and outcome indicators (3rd ed.). https://www.nursingworld.org/nurses-books/ana-books/ebook-essentials-of-genomic-nursing-competencies-/

Exposome and exposomics. https://archive.cdc.gov/www_cdc_gov/niosh/topics/exposome/default.html

CDC. (2024, October 8). About adverse childhood experiences. https://www.cdc.gov/aces/about/index.html#cdcreference_11

Genomics Education Programme. (2022, February 23). Genomics Glossary. https://www.genomicseducation.hee.nhs.uk/glossary/

Gill, K. (2018, September 18). What is synaptic pruning? Healthline. https://www.healthline.com/health/synaptic-pruning

Harden, K.P. (2023). Genetic determinism, essentialism and reductionism: semantic clarity for contested science. Nature Reviews Genetics, 24, 197–204. https://doi.org/10.1038/s41576-022-00537-x

NIH: National Library of Medicine. (n.d.). What are genomic imprinting and uniparental disomy?: MedlinePlus Genetics. https://medlineplus.gov/genetics/understanding/inheritance/updimprinting/

National Health Service (NHS). (2023).The 2023 genomic competency framework for UK nurses. https://www.genomicseducation.hee.nhs.uk/wp-content/uploads/2023/12/2023-Genomic-Competency-Framework-for-UK-Nurses.pdf

National Human Genome Research Institute (NHGRI). (n.d.). Talking glossary of genetic and genomic terms. https://www.genome.gov/genetics-glossary

Organization of Teratology Information Specialists (OTIS). (2023, February 1). Critical periods of development. Mother to baby | Fact sheets – NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK582659/. CC BY-NC-ND 3.0.

Padmanabhan, V., Cardoso, R. C., Puttabyatappa, M. (2016). Developmental programming, a pathway to disease. Endocrinology, 157(4), 1328–1340.

Turkheimer, E. (2024). The nature-nurture question. In R. Biswas-Diener & E. Diener (Eds), Noba textbook series: Psychology. Champaign, IL: DEF publishers. http://noba.to/tvz92edh . CC BY-NC-SA 4.0

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Precision Healthcare: Genomics-Informed Nursing Copyright © 2025 by Andrea Gretchev, RN, MN, CCNE is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.