Chris' DNA Page

Date: [unknown] [unknown]
Location: [unknown]
Surname/tag: dna

Contents 1 Chris' DNA Page 1.1 Common Questions 1.2 Types of DNA Analysis 1.3 YDNA Simplified

Chris' DNA Page

Common Questions

1. How do I upload my DNA to WikiTree WikiTree has no facility to upload your DNA data. You can, however, tell WikiTree about the DNA tests that you have taken, and it will indicate, on all profiles that are genetically linked to you, the expected amount of shared DNA. This will usefully notify yourself, and others, of potential matches.
2. Which company should I test with? It's complicated. Each company has their own database of customers, so if you test with company A you will only be matched against company A's customer database. Each company may also have a target demographic, and if you have Asian ancestry it might be more fruitful to use a company that targets that market — instead of one that has better coverage of North America or Western/Eastern Europe. That said, some companies allow you to upload your DNA data into their database — either for free (for basic usage), or for a small cost (for more advanced tools). So the most economical strategy would be to test with a company that does not allow uploads and has the best coverage of your ethnicity, and then upload your DNA to all the companies that allow you to do so.
3. Why does Company A tell me I'm 25% Cobar, but Company B say's I'm 100% Dubbo? It's all about the customer database that each company possesses. Let's say Company A has customers in Broken Hill, Cobar, and Dubbo. Let's also say Company B only has customers in Dubbo and Bathurst. If you're from Broken Hill with a grandparent from Cobar, then Company A will correctly state you are 25% Cobar. Company B, however, has no information concerning Cobar, but Dubbo is closer to Cobar than Bathurst, so it will state you must have Dubbo ethnicity.

Types of DNA Analysis

There are three main types of DNA Analysis available to consumers:

1. Autosomal — this is the one everyone is familiar with (offered by companies such as FamilyTreeDNA, Ancestry and MyHeritage). It looks at parts of all of your chromosomes, and can find similarities between individuals that likely come from shared ancestry somewhere in their trees. It is limited in how far back through the generations it can reach.
2. Y DNA (available at FamilyTreeDNA) — this is a test that focusses exclusively on the Y chromosome, and therefore can only be taken by individuals that possess one (typically born male). It traces the male line back (son to father to father to father to father...) into deep time. It therefore follows surnames back (in Western cultures) to before the advent of surnames.
3. Mitochondrial DNA (mtDNA) (available at FamilyTreeDNA) — this analyses the DNA found in the mitochondria within your cells. You get this, exclusively, from your mother. It therefore traces the female line back (child to mother to mother to mother...).

When you submit a sample for analysis by any of these companies, they are essentially determining the sequence of chemicals that form your DNA. There are only four chemicals, denoted by the letters A, C, G and T.

Half or your autosomal DNA comes from your mother, and half from your father. Given that half of your mother's DNA comes from her mother, and half from her father, it makes sense that you inherit about a quarter of your DNA from each of your grandparents. It's not exact, because the half you inherited from your mother might be more from her father than from her mother, but as a general rule it's a start.

YDNA Simplified

YDNA is made up of long sequences of four compounds that are indicated by the letters A, C, G and T (after the first letters of their chemical names).

So a segment of YDNA might be written down like:

TCGG ATGC ATGG TACG TACG TCAC CTAA

(I've put spaces in to make it easier to read).

Each time a father has a son there is the possibility of a change (mutation) in the son's YDNA that makes it slightly different from his father's. This can happen in two ways:

1. A single letter change (called a SNP - think "SNiP" for single change)
2. A change in the number of repeats of short sequences (called an STR - think "STRing" for sequence change)

Given the sequence above, a SNP change would look like:

Father: TCGG ATGC ATGG TACG TACG TCAC CTAA

Son: TCGG GTGC ATGG TACG TACG TCAC CTAA

The A in the father has changed to a G in the son.

And a STR change would look like:

Father: TCGG ATGC ATGG TACG TACG TCAC CTAA

Son: TCGG ATGC ATGG TACG TACG TACG TCAC CTAA

There are two repeats of TACG in the father, and three in the son.

STRs change more frequently than SNPs.

Haplogroups are simply a way to give a name to a specific set of mutations, rather than spell it all out. In the SNP example above the father would belong to one haplogroup, and the son to a derivative haplogroup.

Think of the haplogroup name as the name of the man that was first to have the mutation - so instead of R-BY20622, let's call it HGCarl (Haplogroup Carl).

Let's build a family tree where every father has two sons. I've marked every son that has a SNP change with a *, and annotated each with their haplogroup in brackets.

Adam (HGAdam)
│
├─ Bert (HGAdam)
│   ├─ Dirk (HGAdam)
│   │   ├─ Hank (HGAdam)
│   │   └─ Ivan (HGAdam)
│   │
│   └─ Eden * (HGEden)
│        ├─ Jack (HGEden)
│        └─ Kent * (HGKent)
│
└─ Carl * (HGCarl)
    ├─ Fred (HGCarl)
    │   ├─ Luke (HGCarl)
    │   └─ Mark * (HGMark)
    │
    └─ Gabe (HGCarl)
         ├─ Nick (HGCarl)
         └─ Owen (HGCarl)

We can see that Adam's son Bert inherits his father's YDNA without change. Bert, in turn, hands his YDNA unchanged to his son Dirk - and Dirk to his sons Hanks and Ivan. All of them, therefore have Adam's haplogroup (HGAdam). Eden has a SNP mutation and I've named his haplogroup HGEden. Eden's son Jack inherits this, but his son Kent has another change that results in haplogroup HGKent.

The haplotree (the family tree of the haplogroups) would look like:

HGAdam (4 generations old)

│

├─ HGEden (2 generations old)

│   └─ HGKent (current generation)

│

└─ HGCarl (3 generations old)

    └─ HGMark (current generation)

Current generation decendants of Adam (Hank, Ivan, Jack, Kent, Luke, Mark, Nick and Owen) represent all of the derivative haplogroups of Adam. If Kent or Mark do not have male children, then their specific haplogroup (HGKent or HGMark) would die with them.

I've marked the age (in generations) next to the haplogroup, for reference.