Factors of HD (Human Development)

Human Development in Psychology, is concerned with the progressive behavioral changes of an individual from birth until death. It is the study of changes that occur in human beings over the course of their life span. Factors of Human Development can may be cause of Heredity or Environment. In Human Reproduction, the XX is for the female and the XY is for the male. Their offspring can be a single offspring or twins. Twin offspring can be identical, fraternal or siamese. Around one in three sets of twins is identical. This occurs because the fertilized egg divides in two while it is still a tiny collection of cells. The self-contained halves develop into two babies with exactly the same genetic formation. Identical twins share nearly 100% of their genes meaning that most differences such as the height, intelligence, susceptibility to boredom, depression etc. is due to experiences that one twin has but not the other twin.  Identical twins can be also called, monozygotic (MZ) twins. Fraternal twins or dizygotic twins (DZ) share about 50% of their genes. Around two in three sets of twins are fraternal. Two separate eggs are fertilized by two separate sperm, resulting in fraternal or dizygotic twins. These offspring will be no more alike than siblings born at separate times. They can be either same or different sexes, with the odds roughly equal for each. Siamese or conjoined twins identical twins joined in utero. Two contradicting theories exist to explain the origins of conjoined twins. One is the theory of fission, in which the fertilized egg splits partially. Second is the fusion, in which a fertilized egg completely separates but stem cells find like-stem cells on the other twin and fuse the twins together. Siamese twins share a single common chorion, placenta, and amniotic sac, although these characteristics are not exclusive to conjoined twins as there are some identical twins but non-conjoined twins that also share these structures in utero.

Back to Human Development, it can be that the growth of an individual is affected by its Heredity or DNA or by the Environment? When you were born, it is already given what your gender really is or you are free to choose what you want to be? The following are the Genetic Defects in Human Development:

• Turner Syndrome also known as Gonadal Dysgenesis encompasses several conditions in human females, of which monosomy X, absence of an entire sex chromosome is most common. It is a chromosomal abnormality in which all or part of the sex chromosome is absent or has other abnormalities. There are characteristic physical abnormalities, such as short stature, swelling, broad chest, low hairline, low-set ears and webbed necks. Females with tis syndrome typically experience non-working of ovaries which results in amenorrhea or absence of menstrual cycle.
• Klinefelters also a XXX, XXY syndrome is a genetic disorder in which there is atleast one extra X chromosome to a standard human male karyotype for a total of 47 chromosomes rather than the 46 found in genetically normal humans.
• Down Syndrome also known as trisomy 21 is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is the most common chromosome abnormality in humans. Typically associated with a delay in cognitive ability like mental retardation and physical growth. 

Being a human being, we experience different stages as we get older, the first stage is the ovum or egg cell. Second is the embryo, fetus, birth, infancy, babyhood, childhood, puberty, adolescence, adulthood, middle-age, old age and the last in the stage is the death. 

There are 3 ways to achieve immortality in life: the first one is plant a tree, next is write a book and the last one is bear a child.