(MUSIC). Have you noticed that you're different to your relations, parents, or carers,
your next door neighbor,
the kid who lives across the street,
and everyone else on the planet?
In fact, you're unique.
But do you really know why you are different?
Why are we all different to each other?
Why does any organism have different characteristics to another organism?
The answer lies in a long-running debate called nature versus nurture,
or genetics versus environment,
which is a little less catchy.
Nature refers to our genetics.
The unique combination of genes that we have naturally
inherited from our biological parents from their DNA.
Many characteristics are controlled by our genes,
including our blood group,
eye color, or natural hair color.
Some diseases are also caused by our genes.
For example, cystic fibrosis.
The color of a flower or a fruit is controlled by genes in plants.
Nurture refers to the effect of the environment on characteristics.
The word literally means care.
Examples of characteristics that are determined by the environment
are weight or mass,
which is dependent on your diet
or the presence of a scar.
Some diseases may be caused by environmental influences such as type 2 diabetes
or coronary heart disease.
Imagine a plant has not received enough sunlight or water,
this may influence the height of the plant
or the number of fruits produced.
We would say that the environment has influenced these characteristics too
or that a plant has been affected by nurture.
Can you decide if each of these
characteristics is controlled by inherited characteristics,
the environment, or both?
Where would each go on a Venn diagram?
Pause the video while you think.
Did you get them all right?
The effect of genetics and the environment on
characteristics has been researched using identical twins.
Can you think why this is?
Identical twins have identical DNA,
so in theory, should have identical characteristics.
It follows that any differences between a pair of identical twins
could be due to the influence of the environment on their characteristics.
In fact,
twins often grow up to have very different
personalities and preferences beyond their physical similarities.
These studies showed that many characteristics are
influenced by both genetics and the environment.
Some studies actually used twins identical genomes as a control
to prove the effect of the environment on the body.
For example,
one study showed how skin aged differently
by comparing smoker twins with non-smoker twins.
Remember that the characteristics of a living organism
are influenced by its genetics and its interaction with the environment,
so both nature
and nurture are responsible.
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