- [Narrator] People
are born with
all sorts of
different eye colors.
But why?
What causes our eyes
to be different colors?
And why aren't the all the same?
Let's find out on
today's episode of,
- [Cosmic Voice]
Colossal Questions.
- [Narrator] The color of
your eyes has to do with
the amount of melanin
you have in your iris.
Melanin is a pigment,
or natural coloring
found in animal tissue.
It gives our skin
and hair their color,
and our eyes are no different.
Having less pigment
gives you blue eyes.
Having a little bit more
will make your eyes green,
and if you have lots of
pigment, it leads to brown eyes.
You or someone you know might
have different eye colors,
or patches within one eye.
For instance, blue eyes
with green around the edges,
or green eyes with brown
around the irises are common.
When this happens, it's
because different areas
within the actual eye make
different amounts of
melanin, changing the colors.
What color eyes you
end up with is genetic,
meaning it's passed
down from your parents,
even if you don't share
the same eye color.
Science is still trying to
understand exactly what genes
in our eyes get passed down
to determine our eye color.
So far, the key gene in brown
eyes has been discovered,
but experts have
had no luck so far
uncovering the gene
for green eyes.
Okay, so that's why people
have different colored eyes,
but one question remains.
What about the one in
every 100 Americans
who have two different
colored eyes?
Just about every baby
is born with gray eyes,
but in the first several
months after you're born,
the color in the
irises develops, giving
you your eye color.
The melanin levels
in a baby's eyes
determine how dark
their eyes become.
However, for those one in 100,
the amount of melanin in
each eye isn't uniform.
This is called heterochromia.
Complete heterochromia happens
when each eye is
one distinct color.
Central heterochromia,
on the other hand,
is when your eyes have multiple
colors mixed across the two.
But don't worry.
Not only is heterochromia a
completely harmless condition,
but it can look
kind of cool too.
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