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{{languages}}Everybody following genealogy publications will have encountered the use of genetics in genealogy: hereditary diseases, genetic markers, ..etc.
{{stub}}=== Mithocondrial DNA Haplogroups === The same rationale and possibilities as given in Y-DNA Haplogroups apply, with the difference than Mithocondrial DNA (mtDNA) is transmitted trough the female line, and contrary to Y-DNA both males and females are able to test for it (even though it is female inherited, meaning that the mtDNA of a male is completely inherited from the mother).
→See also
Here we give an overview of what type of genetics data is important in genealogy.
==Introduction==
Humans have 23 pairs of chromosomes which form contain their [[Genealogy_Glossary#dna|DNA ]] (deoxyribose nucleic acid). Each of us inherits one half of each pair chromosome from one parent, and the other rest from the second other parent. From the mother one also inherits one cell a piece of which these chromosomes form genetic information that is contained outside the nucleusof the cell. However, this cell also contains some This genetic material which is not part of the human a chromosome, and is called mitochondrial DNA (mtDNA), and also essential for our survivalis passed nearly unchanged from a mother to her child. A special role 22 of the chromosomes are called autosomes, the 23rd chromosome is given referred to as the sex chromosome. For females this is a pair of the sex chromosome contains 2 X chromosomes, one from the mother, one from the fathereach parent. For males however this pair consists of a A male inherits an X chromosome inhereted from the his mother, and a Y chromosome, inhereted from the his father.
At each generation, a child's chromosomes are formed by a random combination of their parents 23 chromosomes. The 22 autosomal chromosomes are passed through to the children, constituted formed of material from the 23 chromosome pairs a random combinaton of the parentsDNA. Over time, mutations also happen, meaning that parts of This process tends to copy segments rather than individual locations while discarding the unchosen DNA. This is how 2 siblings will share DNA but not have identical copies with one another but yet have significant identifiable in common. The 23rd chromosome are whether X or Y is passed from the donor parent whole and is not identical subject to this recombining process. In a male tests can distinguish the same X and Y parts on of the chromosome thus identifying genetic material from the mother and father. In a female the test can identify the DNA of 2 separate Xs in the parentschromosome but cannot identify which was donated by each parent. Mutations The other process that are can alter DNA is called mutation. Mutation simply means change and does not lethal are called variantsimply any negative consequence, although sometimes an accumulation of mutations can be dangerous. Some Significant mutations happen fast, some are quite slowto appear, and some very slowperhaps one or two every few generations. Should If there be were no mutation mutations it would be impossible to tell how related people are one from the otherdistinguish ancestral lines, we would all carry identical DNA. Fast mutations allow researchers to distinguish family groups recently in timegenealogical timeframes, several hundred to a couple thousand years. Slow mutations , such as those that appear in the mtDNA or on the Y chromosome, allow researchers to distinguish race groups up to by analyzing ancient migration patterns, e.g. the saxon migration into Europe.
===Privacy===
*if you share information with other researchers, only share the public data
For harmless genetics data, it is usefull useful to publish the data anonimized anonymized on a public forum. You can do that eg here on this wiki, but note that your account details will be visible in the history, so you might consider to send it to one of the administrators, or create a fake login for this reason.
Eg, DYS information is usefull to relate family branches, so publishing 'last name, region of birthplace, DYS codes' gives other researchers a forum to see how related they are to you.
The less differences, the more related a person is to the person of which the profile is investigated.
=== Y-DNA Haplogroups ===
Less specific than STR markers, a haplogroup is defined by certain SNP mutations that occur infrequently. It is less useful for estimating degrees of relationship between individuals but useful in a broader way, since it deals with whole populations. A Y-DNA haplogroup will be the same for every male in the direct paternal line (father, father of father, father of father of father, etc), except when a "non-paternal event" occurs (i.e. there isn't a genetic contribution from the legal and recognised father).
One way to use this information in a genealogy program is to allow one to stipulate the haplogroup (I2, R1b, J1a1, etc.) for an individual, and cascade that change upwards through the male line. Then allow for a way to break this chain, possibly marking the fact with a flag or visual cue.
An example: a researcher tests for Y-DNA haplogroup and gets the result as R1b1. It fills the "Y-DNA Hg" attribute with "R1b1" and it is cascaded upwords (and downwards) through all the relevant lines. Donwards doesn't only apply to direct progeny: all the cousins that descend though a paternal line from a common ancestor should also be marked R1b1.
Six months latter a cousin (which should be R1b1) makes the same test and gets haplogroup J2. The initial assertion is clearly wrong, and going upwards the genealogy software could pinpoint the most recent male ancestor and flag the discrepancy. This isn't limited to this kind of situations: we now have the haplogroup of several individuals deceased a long time ago, so this "most remote ancestor" could be in the 16th century.
The relevance of this method is not limited to finding mismatches: the much more common situation is that different tests from different lines will yeld the same result. It even allows one to have a good idea of a certain person haplogroup without making a test.
==M-line research==
==Hereditary diseases/traits==
This information of today, can shed light on some strange facts in your family trees history, eg many male early deaths, ...
To be able to extrapolate known facts of today to the past, you need some knowledge: * is it inherited from the father or mother?
* what is the possibility of inheriting the trait?
* under what conditions does the trait show itself?
'''Privacy''': keep this information private. Although you might not mind letting the world know men in your family are bold at 40some of these details, your cousin twice -removed looking for girl might think otherwise.
==Family trees for genetic research==
It allows them to investigate traits and deviations in a broad testfield, while knowing how related the samples are.
==LinksSee also==* [[Addon:DNASegmentMap|DNA Segment Map]] addon Gramplet* [[Addon:FamilyTreeDNAGramplet|FamilyTree DNA]] addon Gramplet* Feature Request {{bug|8919}}: Haplogroup feature?* [https://gramps.discourse.group/t/gramps-and-recording-and-comparing-dna-matches/220 Discourse discussion thread] about the preliminary Haplogroup feature* [https://sourceforge.net/p/gramps/mailman/gramps-users/thread/1224707734.29730.8.camel%40localhost.localdomain/#msg20615232 Event for Y-DNA data] - gramps-users archive 2008 discussion thread*[http://en.wikipedia.org/wiki/Genealogical_DNA_test Wikipedia: Genealogical Dna test]
[[Category:Genealogy]]
