Genetic Genealogy Services
Glossary of Terms
Centimorgan
A Centimorgan (cM) is a unit of measure commonly used in DNA analysis. In the fullest technical sense it is very complicated. However, for genealogical applications it can be viewed as simply a unit of measure much as and inch or a centimeter. #centimorgan
Chromosome
A Chromosome is a structure found inside the nucleus of a cell. A chromosome is made up of proteins and DNA organized into genes. Each human cell normally contains 23 pairs of chromosomes. #chromosome
DNA
DNA is an acronym for DeoxyriboNucleic Acid. It is a polymer composed of two polynucleotide chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. DNA and ribonucleic acid are nucleic acids. #dna #deoxyribonucleicacid
Genetic Genealogy
Genetic Genealogy is the use of DNA analysis in conjunction with traditional genealogical research to trace ancestry. Just as there are many kinds of records and clues in traditional family research, DNA should be viewed as an additional record. It is no more or less conclusive than any other record. Genetic Genealogy can be used to confirm or disprove a family relationship derived from traditional paper trail genealogy. It is vital in tracing unknown parentage from adoptions and sperm donor cases. More recently, Genetic Genealogy has proven valuable in the field of forensics. It has been successful in pointing law enforcement to perpetrators of cold cases as well as contemporary crimes. It has also been used to identify unknown human remains. #geneticgenealogy
Match
When two or more individuals share identical segments of DNA it is considered a match. The length and number of identical segments are a direct indication of the closeness of the relationship between the two people. The length of the matching segments are measured in Centimorgans (cM). The closest match possible (other than that of identical twins) is between a parent and child. A parent and child share approximately 3500 cM of DNA.
Mitochondrial DNA
DNA is either nuclear (found in the nucleus of a cell) or mitochondrial (mtDNA) which is found in the mitochondria of a cell. Since the mitochondria is passed on in the egg, the reproductive cell from the female, it is passed on to all of her children, both male and female. Only females pass on mtDNA. #mtDNA #mitochondrialDNA
NPE
Originally NPE was the acronym for Non Parental Event. More recently it can be used to mean Not the Parent Expected. It can be used to describe a variety of events such as adultery, adoption or other events where the child is not the biological offspring of the expected father. Sometimes this is readily apparent to those who are contemporary to the event, sometimes not.
SNP
SNP is short for Single Nucleotide Polymorphism. Pronounced “Snip”. This refers to a mutation within the DNA of the genome. Various mutations occur at a predictable rate so these mutations are useful for tracing an ancestral line over and extended period of time, such as thousands of years.
Y-DNA
A human genome is made up of 23 pairs of chromosomes. In each pair, one chromosome comes from the father and the other comes from the mother. Pair #23 are the chromosomes that determine the gender of the person. Females are have two “X” chromosomes and males have one “X” and one “Y” chromosome. The “Y” chromosome can be tested and compared with other men. It therefore follows the direct male line often associated with a specific surname. So, two men with matching Y-DNA share a common male ancestor at some time in history. The Y chromosome does not undergo recombination. Therefore, it is passed on basically unchanged. However, mutations do occur. These mutations can be tracked and analyzed. They then become the basis for assigning men to a haplogroup. #YDNA #haplogroup
