DNA is an interesting tool. It first became available after scientists discovered it could be used as an investigative tool for connecting family members and tracing DNA evidence. Because it passes our chromosome to the next generation, it has become the newest tool to help discover family and break down brick walls created by wars, adoption, migration to new states or countries, NPE's (non parental events) and even the purposeful changing of names.
There are 4 types of DNA. 1. YDNA 2. Autosomal DNA 3. X DNA and 4. MtDNA
Each have different truths they can reveal and in different patterns and ways.
YDNA
YDNA
Y Dna comes through the sex gene the Y Chromosome. Males carry 1 Y chromosome from their father and 1 X chromosome from their mother. The Y chromosome is passed down from father to son. So this means a living male descendant can have his YDNA tested and it will show matches that are part of his direct male to male line. An exact match means the two testers are of the same paternal line.
A 1-step off means that match is back at least one generation. 2-steps 2 generations. etc. So Tom Smith will share an exact YDNA match with is father, brothers, paternal uncles, paternal male cousins, grandfathers. YDNA can work well if the surname does not change. Sometimes with NPE (Non Parental Experience) the surnames may not be the same. Or if the culture of the community is matriarchal the surname may be different.
The only caveat is that YDNA can morph and slight changes can occur between generations. YDNA also gives you the Haplo group your paternal line descends from. Haplo-groups are ancient connections in the Family of Man Family Tree.
XDNA
XDNA
X Dna comes from the mother's sex gene the X Chromosome. Females carry 1-X chromosome from their father and 1-X chromosome from their mother. Males carry 1- X gene from their mother and 1 -Y gene from their father. Like the Y DNA it traces through the generations and can be used to trace family lines back. (see the chart above). While the tracing of X chromosomes for family history work is not as accurate as YDNA, when used with a family tree that has documentation, it can help to prove or disprove genealogical hypothesizes.
MtDNA
MtDNA
MtDNA is Mitochondrial DNA that is found only in the egg of the mother. It is therefore, like the YDNA a mother to mother or mother to daughter link to our ancestry. Unlike the YDNA MtDNa does not morph - hardly ever! So my MtDNA that I have is the same as my 20th great grandmother. It is the same as my daughters and granddaughters. It is not easy to trace because of the cultural custom of using paternal names for familial identification, so maternal names change with each marriage. For well documented family trees MtDNA information can be used for verification of ancient bones. Google it there is a very famous case from England that involves MtDNA evidence. King Richard III
Autosomal DNA 
Randomness
Autosomal DNA
Autosomal DNA comes from the 22 chromosomes that are not sex chromosomes or the MtDNA found soley in the mother's ovum egg cells. All 22 chromosomes are where we get our individual traits from. It is where your gene for a cleft chin would be stored, or green eyes, or freckles. The 23rd chromosome is the sex chromosome as described above.
The AuDNA is valuable because it can help find your people. It is the DNA that can be triangulated with others and help lead you to the correct Family History pathway.
It is not perfect and has times when it can be misleading, but for the most part when coupled with documentation, family lore and knowledge it can help prove relationships.
AuDNA used with a cousin calculator can help you discern the most probable relationship with your DNA match. Basically, the more cMorgans, the closer the relationship.
Randomness
DNA distribution DOES NOT FOLLOW PATTERNS! It is RANDOM!
After the 1st generation, (1st cousins), DNA is random. This means that your 2nd cousins may or may not get your great grandfather's cleft chin.
You receive 50% of each of your parents DNA, 25% of your Grandparents, 12.5% of your Great Grandparents, 6.25 % of your Great Great Grandparents, 3% of your Great Great Great Grandparents, 1.5% of your Great Great Great Great Grandparents. etc. So by Autosomal DNA is only reliable to the 6th generation. After that it is only reliable if you have documentation that proves the hypothesis of relation. The possibility of false positive and other variations greatly increases the farther back in your tree you go. SO GETTING DNA FROM YOUR OLDER GENERATIONS IS EXTREMELY IMPORTANT. WHEN they pass away they will take valuable DNA evidence with them. 
In addition, t
his is why getting your cousins to do DNA testing is very helpful. Not every 2nd cousin will get all of the DNA from your shared great grandfather. Each and every member of the family will carry important DNA puzzle pieces.
his is why getting your cousins to do DNA testing is very helpful. Not every 2nd cousin will get all of the DNA from your shared great grandfather. Each and every member of the family will carry important DNA puzzle pieces.
No comments:
Post a Comment