DNA Jargon

Admixture The autosomal DNA test ethnicity estimates.

Alleles “An allele is one of a pair of genes that appear at a particular location on a particular chromosome and control the same characteristic, such as blood type or colorblindness.” Vocabulary.comBelow you can see I inherited the Allele C from each parent. The two together are a genotype. My genotypes here are good. Sometimes they cause disease.

centiMorgan (cM) “A centiMorgan (cM) is a measurement of how likely a segment of

DNA is to recombine from one generation to the next. A single centiMorgan is considered equivalent to a 1% (1/100) chance that a segment of DNA will crossover or recombine within one generation.” Family Tree DNA

DNA Segment “A DNA segment is any continuous run or length of DNA. It is

described by the place where it starts and the place where it stops.” From Family Tree DNA.

Endogamous “An endogamous population is one where the members usually

only marry within the population group. The bases for endogamy may be geography, ethnic identity, social class, or religion. Long periods of intermarriage have left many endogamous populations with lower than average levels of genetic diversity. Examples of historically endogamous populations are the Amish, the Basque, and the various sub-populations of the Jewish Diaspora.” From Family Tree DNA

Fully Identical Segment “Two individuals are said to share a fully identical region (FIR)

or completely identical region of DNA if the alleles on both chromosomes are identical throughout the region…” Siblings share fully identical regions because they can inherit DNA in the same region from both parents.

The Green in the chart about shows fully identical regions of siblings

Haplogroup “A haplogroup is a major branch on either the maternal or paternal

tree of humankind. Haplogroups are associated with early human migrations. Today these can associated with a geographic region or regions.” From Family Tree DNA

Haplotype “A haplotype is the set of values for a set of DNA values. For example,

the results of the Y-DNA12 test for one person is their haplotype. Two individuals that match exactly on all markers have the same

haplotype.” From Family Tree DNA AncestryDNA uses Haplotypes to phase their results or separate them

according to maternal and paternal sides.

Half-Identical Region (HIR) “A half-identical region (HIR) is when two people share a DNA

segment that’s half matches. The half-identical region may be either identical by descent (IBD) or identical by state (IBS).” From Family Tree DNA site

We receive half of our DNA from our mother or father. Our matches will match on our maternal or paternal side and will share half identical DNA.

Identical by Descent (IBD) Means a segment is inherited from a common ancestor Identical by State (IBS) Means a segment can’t be attributed to a common ancestor.

Could be a coincidence or an ancient segment.

Inbreed “In genetics, inbreed refers to someone whose parents are related. It most

often refers to cases where the relationship is within five generations.” Family Tree DnA

New Ancestor Discoveries NAD You might hear AncestryDNA testers referring to NAD’s. They are talking

about the “New Ancestor Discoveries” you find on your DNA home page. I’ve found these are generally not ancestors. They generally point to cousins.

DNA Segment mapping Using autosomal segment data provided by companies like

23andMe and Family Tree DNA to create a map of all your shared segments. Kitty’s DNA Mapper website allows you to create maps with segment data from any source.

Phasing Separating DNA by Maternal and Paternal sides.

Triangulation Is when 3 or more people match on the same segment. This is

where the chromosome mapping, and chromosome browsers at 23andMe and Family Tree DNA come in handy.

Single Nucleotide Polymorphism SNP’sDNA copying errors. The more SNP’s we share the more closely related we are. Below you can see a sequence that repeats until a copy error occurs, and we get a G instead of a C. A A T C G TA A T C G TA A T C G T A A T G G T