The Role of Genetics on Development
What makes our personality- genetic inheritance or the result of the environment, including parenting, social experiences, friends, family relationships and education? Modern scientists and researchers agree that we are a complex combination of both genetics and environment. Nevertheless, genetics is widely recognized as a determinative factor of a successful human mental and physical development. Thus, the problem of various genetic disorders and abnormalities remain urgent in modern science.
Gregor Mendel was the founder of genetics. While growing peas in the monastery, Mendel noticed that some traits of a plant were more predictably displayed in its offspring. These traits can be either dominant or recessive. If the parents’ genes contain the same trait or disorder it will be expressed. If the genes are different, the dominant trait will be expressed. This was called the Mendelian law (Nüsslein-Volhard, 2006, p.7). The same law is applied to the human reproductive process. It is known that children inherit both their parents’ traits and the transference of these traits is known as heredity (Nüsslein-Volhard, 2006, p.25). These can be some physical traits (color of eyes or hair, complexion, constitution) and psychological (IQ levels, shyness, cognitive abilities, love for adventure). Some of these qualities can be influenced by the environment but others are predetermined by parents’ genes and are transmitted through parents’ DNA to offsprinhg. In the process of fertilization a male reproductive cell (sperm) and a female reproductive cell (ovum), each containing a set of chromosomes with genes, unite their 23 single chromosomes into a single cell of 46 chromosomes. The genes are made up of chemical structures of DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) which determine the whole life of the offspring. However, some errors may occur and a child gets more or fewer than 46 chromosomes; then genetic chromosomal disorders take place (Ashford et al., 2010, p.57). These disorders may disrupt the normal development of a person. Nowadays, researchers agree that there are three major levels of genetic disorders single-cell or inherited disorders, chromosome disorders (containing extra, missing or damaged autosomes) and multifactorial disorders (Ashford et al., 2010, pp. 57-59; Kail &Cavanaugh, 2012, pp.45-49).
Single-cell disorders are hereditary disorders which occur due to a defect or an absence of a single gene and include such disorders as sickle-cell disease and cystic fibrosis. These disorders occur when a single gene is either defective or missing. For example, in the case of a sickle-cell disease a person inherits two recessive alleles on a chromosome 11, which is responsible for red blood cells formation. Such people have sickle-shaped blood cells that tend to clump together and block the blood vessels, which cause poor transport of oxygen in the organism. As a result, people with such disease show signs of mild anemia when they are seriously deprived of oxygen (Kail &Cavanaugh, 2012, p. 45). Parents of a child with a sickle-cell disorder should take precautions in order to avoid crisis. Regular doctor’s appointments should be scheduled for such children and special attention should be taken for certain infections, medication that restricts blood vessels, too much exercise and high altitudes. Parents should also be aware of a delayed sexual maturity and stunned growth. In general, the life prognosis may be positive if the parents and the child himself act adequately and manage to avoid sickle-cell crises.
The second type is chromosome disorders. Such disorders occur when “an alteration takes place either in the structure or the number of chromosomes”. In fact, they are “malformation of chromosomal pairs at the time of conception” and include Down syndrome, fragile X-syndrome, muscular dystrophy and some metabolic disorders (Ashford et al., 2010, p.57). The best example of a chromosomal disorder is a Down’s syndrome. As Ashford admits, Down syndrome was “the first chromosome abnormality identified by scientists”. In 95% of cases the disorder occurs due to trisomy of chromosome 21 (Ashford et al., 2010, p. 61). For certain reasons chromosome 21 does not separate during meiosis and a child receives one number 21 chromosomes from one parent and two numbers 21 chromosome from the other. This disorder disrupts both physical and mental development of a child, though these abnormalities may not be visible during the first several months of life. People with Down syndrome possess unique physical characteristics: they are usually of a small height, with a flattish small nose, almond shaped eyes, a fold over the eyelid, smaller head and neck. Their mental and behavioral development is retarded for months or even years in comparison to healthy children. Parents of children with Down syndrome face a lot of challenges in the preschool period and during the school years; as such children require special educational programs. Comprehensive approach to rearing a Down child may increase the chances for a better quality of life and greater independence. Though specific environment can improve cognitive and learning abilities of such children, they are still rather limited and their life expectancy is not long – from 25 to 60 years (Kail &Cavanaugh, 2012, p. 46). No one can feel secured against having a baby with a Down syndrome but the risks dramatically increase with the older women. The reason for this phenomenon lays in aging and deterioration of a woman’s egg, aging of a whole organism, which now fails to recognize abnormalities at the early stage and abort the damaged egg, and also unfavorable conditions and difficult environment which the woman has been exposed to during all her life (X-ray radiation) (Kail &Cavanaugh, 2012, p. 47).
The last major group of genetic disorder is multifactorial disorders which are caused by multiple genes and environmental factors (Ashford et al., 2010, p. 60). These are Alzheimer’s disease and hypothyroidism. It is usually difficult to say which factor is responsible for development of this or that condition. For example, many people who have relatives with cancer never develop this disease.
Summing it up, we may say that genetics has a great influence on a person’s development. The genes with all information and instructions for future life are given to a child at the moment of conception. Though most of the defected eggs are aborted naturally at the early stages of their development, some abnormalities still occur and lead to the genetic disorders in offspring. These abnormalities may vary from mild and insignificant to very severe and life-threatening. Researchers all over the world work hard to find out the causes of genetic chromosomal disorders and to develop effective preventive measures.
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