"I proposed to my cousin."
"Is this a joke?"
"No."
"Drew, what the $#%*!"
"What?"
"This is like embarrassing
for you."
"I'm sorry."
With so many varieties
in our skin tones,
hair colors,
and features,
the human race
is a marvel of evolution.
But what if we all decided
to preserve our family traits?
What if everyone started
inbreeding tomorrow?
inbreeding might be a topic
reserved for today's daytime talk shows,
it was once a common practice
among royalty.
In 1661,
Prince Charles II of Spain
was born to parents
who were uncle and niece.
Unable to speak
until he was four
or walk until he was eight,
he was the product of centuries
of inbreeding.
Genetically speaking,
his family history made Charles II
more inbred
than a child born
to a brother and sister.
So, if we all started inbreeding,
First, let's clear up any confusion.
Inbreeding is when two close relatives
have a child together.
Inbreeding is how early humans survived
when there were not many people
on the planet.
But 75,000 years ago,
humanity almost faced a similar fate.
The Toba volcano erupted in Indonesia
75,000 years ago,
exploding with the force of
The debris and clouds
blacked out the sky
for almost six years,
plunging Earth into an ice age.
It nearly wiped humanity
off the face of the Earth.
According to geneticist Dr. Barry Starr,
there were no more than
1,000 breeding pairs
of humans left.
And with so few people,
humans were forced to repopulate with,
well, whoever was left alive.
And often, that meant your own family.
So to an extent,
we're all a little inbred.
But that 0.1% difference
in our DNA is hugely important.
And if we were to decide
to keep our family traits
in only our families,
we might do some severe damage
to our genomes.
Let's take a closer look.
See, we all have
23 pairs of organized DNA,
called chromosomes,
in each cell's nucleus.
And every pair of chromosomes
has a copy of each parent's genes.
Some animals are inbred
for their desirable traits.
Inbreeding may have given your dog
its loveable, floppy ears.
But in humans,
the results may not be so cute
or desirable.
If you breed with someone
who has the same faulty genes
that you have,
it could produce a child
who inherits a lot
of medical problems.
In fact,
first cousins have an 8% chance
of having a child
with a problem after birth.
Your kids might develop cystic fibrosis,
a blood disease,
or even heart problems.
But the real damage
would come generations later.
By then,
with less diversity in your gene pool,
it might be harder for your body
to survive changes
in the environment.
Researchers at the
Eindhoven University of Technology
found that inbreeding
may have caused the Neanderthals
to go extinct.
Simulations show that
this early version of humans
lived in small groups.
Their bad genes
caused their birth rates to decrease,
until eventually,
they died out.
And if our descendants
can't adapt easily,
their babies could die more often
than ours do.
So, if you want to decrease
the chance of that happening,
you'll need to breed further down
your family tree.
Interestingly,
a study of Icelandic couples found that
those who married a third cousin
produced more children
than previously unrelated couples.
Let's make it clear.
Inbreeding itself
doesn't create bad genes.
But if you and your partner
have the same bad gene,
it's more likely that you'll pass
it on to your child.
But if both parents
do not have
the same genetic mutation,
their chance of giving birth
to a healthy baby
is the same
as a non-related couple's.
If we all start inbreeding,
and parents become more aware
of the risks to their children,
it might lead to increased monitoring
of the womb.
And parents might choose
who their children mate with,
based on the genetic traits
of their family members.
Generations of children
could have their love lives mapped out
before they're even born.
Since you'd all be marrying
within your family,
you would have a greater need
for genetic counselors.
And for medical professionals
to deal with the genetic diseases
being passed to the children.
If you become
much more aware of the problems
you might give to your offspring,
would you take better care of yourself?
None of us can avoid
a genetic problem
we're born with.
And we don't control
who our parents are.
But you might choose
to control how much
alcohol you drink,
or eat better food,
or even pop a vitamin
now and then.
While some people might think that
they could be preserving a culture
or certain traits through inbreeding,
it might have the opposite effect.
And, like what happened
to the Neanderthals,
if there's not enough cultural diversity,
some genetic traits would just die out.
If something causes our population
to drastically decrease,
we might have to think twice
about inbreeding.
Like, what if there were only
1,000 people left on Earth?
Well, that's a story for another WHAT IF.