Variation

• Variation is the differences in the characteristics of individuals

  in a population.
• The basic characteristics of every individual are the result of the genes they have inherited from their parents.
• However, some differences are entirely due to to the environment you live in. You may have a scar as a result of an accident. Such variation is environmental, not genetic.
• Many differences between individuals of the same species

  are the result of both their genes and the environment.

  For example, you inherit skin colour from your parents but it

  will darken if you live in a sunny environment.

  Height and weight are also affected by both genes and the

  environment.
• Variation can be investigated by looking at identical twins

  who have been separated at birth.

  Any differences between the twins will be caused by the

  environment as they are genetically identical.