Having free or attached ear lobes is a genetically controlled characteristic, whereas you do not inherit the ability to play a musical instrument. This must be learned. The study of how genetically controlled characteristics are inherited is called genetics. Scientists study genetics to look for patterns in the way that certain characteristics or traits are inherited.
Dominant and recessive genes Scientists have discovered that within a species a single trait may be influenced by a number of different genes. Within the human species there are many different eye colours. This is because there are many different varieties of the genes that influence eye colour. Each individual human has two genes that influence the colour of their own eyes. One gene is inherited from each parent. The genes are described as being either dominant or recessive. A dominant gene may be thought of as being stronger than a recessive gene. When an individual has both a dominant gene and a recessive gene for the same trait, the dominant gene controls the trait. The gene for brown eyes is dominant over the gene for blue eyes. A person with both genes will have brown eyes.
Fig. 8 Eye colour is determined by genetics.
Exploring the patterns Genes are sections of a DNA molecule that control a characteristic. Scientists represent genes using letters. Capital letters represent dominant genes and small letters represent recessive genes. In humans, the gene for blue eyes is recessive and is represented by b. The gene for brown eyes is dominant and is represented by B. Genes usually occur in pairs which gives three possible combinations. The combination of genes control the characteristic.
