Transcript by David Royse, Bruce A. Thyer & Deborah K. Padgett

Human Behavior and the Social Environment: Theories for Social Work Practice
Bruce A. Thyer, Catherine N. Dulmus, and Karen M. Sowers, Editors
Chapter 8
Genetic Theory
by Laura J. Pankow
Human genetics is the study of inheritance, of how features possessed by
one’s parents are passed on to one’s biological children. Genetic influences
are largely responsible for our physical features as well as aspects of our
temperament and abilities. Environmental influences during pregnancy (e.g.,
maternal diet and illness) and after birth can modify the expression of our
genetic endowment. Someone born of very tall parents might have stunted
growth due to dietary deficiencies, for example.
Social work has had a long-standing interest in the role of inheritance and
genetics and there is a modest literature on the topic. The National
Association of Social Workers has produced some practice standards for social
workers involved in helping clients with genetic disorders and their families.
See
http://www.socialworkers.org/practice/standards/geneticsstdfinal4112003.pdf
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Human Behavior and the Social Environment: Theories for Social Work Practice
Bruce A. Thyer, Catherine N. Dulmus, and Karen M. Sowers, Editors
Chapter 8
Genetic Theory
by Laura J. Pankow
Although it has long been known that parental features are passed on to offspring
(e.g., animal breeders have selectively breed livestock with desired features for years;
farmers selectively breed more productive and disease-resistant crops), the scientific
study of modern genetics got its start with the botanical studies of Gregor Mendel
(1822–1884), an Austrian monk, who studied plants, and how characteristics such as
height and color were transmitted across generations.
Mendel quantified how traits were passed on, but he did not develop a satisfactory
mechanism to explain how this occurred. It was not until Watson and Crick published
a 1953 paper in the journal Nature that the correct mechanism was discovered
through which genes carrying DNA were said to be responsible for the phenomenon of
inheritance.
Their one-page paper, for which the authors received a Nobel Prize, can be located
here:
http://www.nature.com/nature/dna50/watsoncrick.pdf
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Human Behavior and the Social Environment: Theories for Social Work Practice
Bruce A. Thyer, Catherine N. Dulmus, and Karen M. Sowers, Editors
Chapter 8
Genetic Theory
by Laura J. Pankow
DNA stands for deoxyribonucleic acid and under a microscope appears to be
structured as a ladder that is twisted into a spiral helix. The sides of this molecular
ladder are made up of sugars and phosphates and the rungs are composed of amino
acids. Sections of DNA are called genes and carry information which structures
how cells reproduce and transmit traits. One DNA molecule has many genes.
DNA is contained within the nucleus of the body’s cells in structures called
chromosomes. When cells divide (reproduce) the chromosomes and their DNA
(hence gene structure) is duplicated.
In humans, the gonads (ovaries in women and testes in men) carry the DNA that is
involved in reproduction. The ovary produces eggs (ova) containing the woman’s
DNA, and the testes produce sperm, which contains the man’s DNA. When the
sperm fertilizes the egg, the egg contains genetic information from both parents.
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Human Behavior and the Social Environment: Theories for Social Work Practice
Bruce A. Thyer, Catherine N. Dulmus, and Karen M. Sowers, Editors
Chapter 8
Genetic Theory
by Laura J. Pankow
Male babies possess an X chromosome from the mother and a Y chromosome from
the father. Female babies possess an X chromosome from each parent. Thus the
father determines the gender of the baby.
Almost all male babies possess an X and a Y chromosome, and females a XX pair.
However genetic diseases are the result of abnormal numbers of X and Y
chromosomes. Individuals possessing an X chromosome but who lack a Y
chromosome display Turner’s Syndrome. Someone with with an XXY pattern will
display Klinefelter’s Syndrome. Fragile X Syndrome is caused by being born with an
XY combination, but where one of the arms of the X chromosome is constricted.
Hemophilia, a blood disorder characterized by impaired clotting ability, is an Xlinked genetic condition, as are forms of color-blindness. Some genetic disorders are
more common in certain groups. Persons of African descent are at much higher risk
to develop sickle-cell anemia, while Tay-Sachs disease is more common among persons
of eastern European Ashkenazi Jewish descent.
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Human Behavior and the Social Environment: Theories for Social Work Practice
Bruce A. Thyer, Catherine N. Dulmus, and Karen M. Sowers, Editors
Chapter 8
Genetic Theory
by Laura J. Pankow
Some social workers specialize in genetic counseling, helping potential parents who may be
carrier of a genetic disorder, decide to have or not to have children. Others provide
psychotherapy to individuals with genetic disorders such as Huntington’s Disease, a form of
cognitive impairment that does not usually manifest until midlife. Some forms of developmental
disability are genetically based and many social work services are provided to such persons and
their families, across the life span.
A general knowledge of genetic theory is important for all social workers to possess, and those
serving clients with genetic illnesses need an in-depth background to be effective helpers.
Some social workers join the National Society of Genetic Counselors to obtain advanced expertise
in this area. See:
http://en.wikipedia.org/wiki/National_Society_of_Genetic_Counselors
It is hoped that advances in genetic research will eventually lead to gene-based therapies, or even
effective treatments for persons with a genetic disease. It is also hoped that at some point it may
be possible to correct a genetic abnormality among carriers.
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