Child Development

Unit 2 / Session 2

Biological factors

As you have already learned, biological factors relate to naturally occurring influences during the growth and development of a child. Many of these influences are passed to the child through genes...this is known as genetic inheritance.

Let’s deepen our understanding of this topic by taking a closer look at genes and how they work.

There are three key areas to understand when it comes to genetics – these are:

  1. DNA
  2. Chromosomes
  3. Genes

Click on the flashcards below to find out more.

DNA

The DNA in our body carries the genetic information that determines our characteristics. Our DNA is found in large, complex molecules in the body and each person’s DNA is unique (apart from identical twins).

Chromosomes

Chromosomes are long strands of DNA, and each single chromosome is made up of approximately 2000 genes. They are found inside the cells of the body. The human body has 23 pairs of chromosomes (so 46 chromosomes altogether) – for each pair of chromosomes, one is inherited from the mother and the other from the father. The first 22 pairs are called autosomes, and they are the same in boys and girls. However, the 23rd pair of chromosomes is what determines the gender of a child. A male will have one X chromosome and one Y chromosome, while a female has two X chromosomes. This combination of chromosomes takes place at the point of fertilisation and determines the gender of the baby.

Genes

A gene is a section of DNA which defines a particular characteristic. For example, one gene will determine hair colour, another will determine eye colour and so on. Genes have different versions, called alleles. For example, the gene for eye colour is made up of two alleles – one for blue eye colour and one for brown eye colour – in these pairs of alleles, one is dominant and the other is recessive. The way in which these alleles combine will determine individual characteristics.