Investigative Genealogist Answers DNA Questions

I'm CeCe Moore, Genetic Genealogist.

I'm here to answer your questions from the internet.

This is Genealogy Support.

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AirSignificant2006 asks,

What's the most interesting discovery

you've made through A DNA test?

One that comes to mind is,

I discovered that LL Cool J's mother was adopted,

and she didn't know it.

The DNA matches were not lining up

with her parents at all.

And so I was able to identify

her biological parents through her DNA alone,

and it was a huge discovery for them,

because LL Cool J had been partly raised

by his maternal grandparents,

so it was very significant to discover

that they were not his biological grandparents at all.

A Reddit user asked,

How did the police actually find a person

just from A DNA sample?

What we are doing

in Investigative Genetic Genealogy,

which is the term that refers

to when we're working with law enforcement,

is we are reverse-engineering someone's identity

from their DNA alone.

And how can we do that?

That is because autosomal DNA

is inherited from all of your ancestral lines.

And so if we can identify your ancestors

from who you're sharing DNA with,

then we can piece your family tree back together,

little-by-little.

And so even if we don't know

who the DNA contributor is,

we can start piecing their family tree back together,

based on the family trees

of the people they share DNA with.

So if you share DNA with four people

who all descend from one set

of great-great-grandparents,

we know that's one piece

of the criminal's family tree,

and he must also be a descendant

of those common ancestors.

A Quora user asks,

Can a person's innocence or guilt be proven

through genealogy tests like ancestry.com?

Well, not directly,

because ancestry.com,

23andMe,

and MyHeritage,

the three largest DNA databases,

have barred law enforcement

for using their services for criminal research.

All of the genetic genealogy databases

are owned by private for-profit companies,

so they get to set their own policies,

procedures and terms of service.

Their reasoning is that they built those databases

and those services

for people to learn about their family history,

not for law enforcement to find criminals,

but then the smaller databases

have made a different decision.

FamilyTreeDNA, GEDmatch

and DNA Justice have specifically decided

to work with law enforcement

and to help us identify violent criminals,

and also John

and Jane Doe's.

So, John

and Jane Doe's are people who have died

without their identification,

who have not been returned to their families.

Their families are out there

still wondering what happened to them,

and we're not even allowed to use

the big databases for those types of cases.

Over 54 million people

have taken direct consumer DNA tests,

but for law enforcement cases,

we are limited to about two-million people

to run these comparisons

and try to identify the contributor of that DNA.

Zachoutloud123 asked,

What is your craziest DNA matches story?

The baby switch ones are probably the craziest to me.

When someone's DNA results don't match up

at all with their family tree,

there are only a couple of possibilities.

One is they were adopted

and didn't know it,

but another one that we're actually finding many of,

is baby switches from the hospital.

I have worked on dozens of those cases

and am aware of hundreds of cases

where people were switched at birth

and were raised with the wrong parents,

and lived a life intended for someone else.

It's assumed that these are accidents,

but we also have some cases

where the theory is that a person

was purposely switching out the babies.

This sometimes happened when a rich couple

had a very ill baby,

a sickly baby

that they didn't think was going to survive,

and a poor single mother for instance,

had a very healthy newborn.

Sometimes they would purposely switch those out

to keep the rich customers happy.

Siliana999 asks,

What is genetic genealogy?

Well, genetic genealogy is the combination

of documentary research or the paper trail,

where you're tracing your ancestors back in time,

combined with DNA.

So, DNA has been used for genealogical purposes

for about 25-years now,

and that really has helped to inform our genealogy.

Everybody has brick walls,

which means they can't get further back

on one branch of their tree.

For instance, you might not know

who your great-great grandparent is

and you're unable to find the paper trail records

to identify that person.

So if you turn to DNA testing,

you then may be able to fill in

those spots in your tree

that were formerly your brick walls.

Markcuban42 on Reddit asks,

What cases have been solved

with the help of genetic genealogy?

Well, over the last eight-years,

over 1,000 violent criminals

have now been identified through genetic genealogy.

I have helped law enforcement

solve over 400 of those cases

with just my small team.

One case that comes to mind

is the little girl, April Tinsley.

She was walking to her friend's house

in Fort Wayne Indiana

and she was kidnapped,

and murdered by a man named John Miller,

and I helped to identify him in 2018.

He was the very first person to be convicted

that had been identified through genetic genealogy.

In December 2018,

he pled guilty to the crime

and received 80-years behind bars,

and he ended up dying in prison.

Rondulfr asked,

Are Europeans really all descended from Charlemagne,

or anyone of that time period?

The answer to that is yes!

Charlemagne was the king of the Franks from 768

and he had at least 18 known children.

That's not just true for Charlemagne,

it's actually true for any person

who lived in the ninth century in Europe

who has descendants.

And that is because our tree grows exponentially

as you go back in time,

to the point where we would have more ancestors

on our family tree than were alive

at that point of time.

A thousand years ago,

we would've had over a billion ancestors,

which is larger than the population

at that time in history.

So any person living over a thousand years ago in Europe

that has descendants today,

is actually the ancestor of all people

who have European ancestry.

And that would also be true,

for instance in Asia,

or any part of the world really,

because our family trees grow out like this

and then they start collapsing in on themselves,

it's called Pedigree Collapse,

so as your tree goes back in time,

it looks more like a diamond.

A user on Quora asks,

What are some reasons

why it's often difficult to trace your lineage

or family history?

Well, it really is dependent

on your population group,

from where your ancestors lived,

because some places have much better records than others.

For instance, if your ancestors are from Iceland,

you might be able

to trace your family tree back 30-generations.

Or Switzerland has records going back over 700-years.

In my own personal family tree,

I've been able to trace back

to the 1400's on my Finish lines,

and that is because they have such fantastic records.

But there are many other population groups

that either didn't keep records,

or they had them

and they were destroyed.

For instance, in World War I,

the Irish pulped their census records

due to a severe shortage of paper,

meaning they destroyed those

and used that raw material for other purposes.

If you have Asian ancestry or Indian ancestry,

there may be scrolls that traced your family tree,

at least the men in your family tree,

back thousands of years.

But you have to be fortunate enough

for those to have survived

and to be able to find those.

And also if you have ancestry

from the Southern United States,

during the Civil War,

many courthouses were burned.

And so you might have family records

that were housed in those Burnt Counties

as they're called,

or if you have Ashkenazi Jewish ancestry for instance,

many of those records were destroyed

during World War II.

A user on Reddit asks,

Can someone explain the whole idea of ethnicity to me?

I was taught by scientists

not to use the term ethnicity

in the context of DNA.

Instead we use terms like Ancestral Origins

or Biographical Ancestry.

And that is because ethnicity

really implies more about

someone's culture or traditions.

Your ethnicity is really what's been passed down

in your family.

And so ethnicity is more of a social term

and Ancestral Origins

or Biographical Ancestry

is more of a scientific term.

Now, ethnicity is used for these tests

because it's easily understood by the public,

and it's good for marketing for instance,

but it's really not the most accurate term

that should be used in the context of genetics.

Potential-Stop-5998 asked,

My husband

and I found out that my great-grandpa

is his grandma's uncle,

and now I'm pregnant.

Should I be worried?

No, you don't have to be worried

about a relationship that distant.

There have been many

first-cousin marriages throughout history,

typically without issues.

I believe for first-cousins,

there's only about a 10% likelihood

that it will have a negative impact

on offspring of that couple.

Unfortunately, I've had to tell hundreds of people

that their parents were first-degree relatives,

which is parent-child or siblings.

NeuralStardust asked,

How far back can we trace using DNA?

For example, the family tree

and the origin of life?

Well, it depends which type of DNA you are utilizing.

Mitochondrial DNA is passed

directly from mother to child.

Only women pass it on.

So you received

your mitochondrial DNA from your mother,

who received it from her mother,

who got it from her mother

and her mother,

and so on,

back hundreds of thousands of years.

If you're using the Y-chromosome

that only men carry,

there is a similar concept

called Y-Chromosomal Adam,

that is the most recent man

that all of men descend from,

or trace back to,

and he lived about 200,000

to 300,000 years ago.

Now, there's a big misconception

that Mitochondrial Eve

and Chromosomal Adam were a couple,

and that's not true.

They didn't know each other,

although they both did come from Africa,

around the same time period.

A Quora user asked,

How long does it commonly take

to solve a case

using high-tech sleuthing

like genealogy websites?

The most quickly I've been able

to help law enforcement solve a case

is in 30-minutes.

And, the longest it has taken,

is eight-years

and counting.

I've been trying to identify a little girl

known as St. Louis Jane Doe

for almost eight-years now,

and that is because she comes from

the African American population group,

of which we have less representation.

And also we run into

that genealogical brick wall at the 1870 census,

where formerly enslaved individuals

were not enumerated by name prior to that.

This one is from RoyalPurp.

I'd bite the bullet

and take a DNA test.

I wanna see how far back

they can trace my ancestry.

Now we're just talking about your own DNA,

not fossil DNA.

It is the same as far as your Y-DNA

can be traced back

hundreds of thousands of years,

your mitochondrial DNA,

at least 150,000 years.

But your autosomal DNA

is really inherited

primarily from your closer ancestors.

We have Genealogical Family Trees

and Genetic Family Trees,

Genealogical Family Trees are all your ancestors

as far back as you can go.

Genetic Family Tree is just the people

who have contributed to your genome.

So we receive DNA

from all of our third great grandparents,

and almost certainly

all of our fourth great grandparents.

But when you get further back in the tree,

some of those ancestors start falling off

your Genetic Family Tree,

and so now you're only inheriting DNA

from a subset of your ancestors.

EngineeringLumpy asks,

Why do siblings get different DNA percentages?

So he's referring to the ethnicity portion

of the DNA results.

And the reason that siblings

don't get the exact same results

is because they inherit different DNA

from their parents.

We overlap with our siblings

on about 50% of the DNA.

So there's some portions

where we inherit the exact same DNA

from both parents.

There's some portions of our DNA

where we inherit the same DNA from one parent,

but not the other.

And then there are some parts of our DNA

where we don't inherit the same DNA

from either parent.

User MandoMonroe00 asks,

I think I wanna take the ancestry DNA test,

but how accurate is it?

It's important to understand

that there are two different parts

of the results you receive

when you take a DNA test.

One of those is to find relatives,

and those are highly accurate.

If they tell you

that someone is your relative, they are.

I see a lot of people who think it's a mistake

when they get a match on ancestry for instance,

that says it is a half-sibling.

And people need to understand,

that can never happen by mistake,

if you share about 25% of your DNA with someone,

that is a very close relative to you.

But the other part of the test

that gets a lot more attention,

is the ethnicity estimate,

that is less reliable in that,

it is a developing science.

They're very good at telling you

what parts of the world you come from

on a continental level,

meaning the Americas versus Africa,

versus Europe, versus Asia.

That is relatively easy to do.

But when they are giving you

these very specific labels,

very granular results,

that's much more difficult to do.

And that's because there's been so much migration

throughout history.

SikoBeanis asked,

Do you realize how much DNA you share

with your cousin versus your third cousin?

So with your first cousins,

you'll share on average 12.5% of your DNA,

and your third cousins,

you'll share on average,

less than 1% of your DNA,

and you might not share any DNA

at all with your third cousin.

Well, that's all the questions we can cover today.

I hope you learned something.

Until next time.

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