FAQ
Link to Family Tree DNA's Glossary:
https://www.familytreedna.com/learn/glossary/
Some Abbreviations and what they Mean:
EKA = Earliest Known Ancestor = The Earliest or most distant from you Ancestor, see MDKA.
MDKA = Most Distant Known Ancestor = Your most distant known ancestor (MDKA) is the furthest person who you have documented on a specific genealogical line. In genetic genealogy, it usually refers to someone on a direct maternal line (the mother, her mother, her mother’s mother, etc.) or on a direct paternal line (the father, his father, his father’s father, etc.).
TMRCA = Time to the Most Recent Common Ancestor = The amount of time or number of generations since individuals have shared a common ancestor. Since mutations occur at random, the estimate of the TMRCA is not an exact number (i.e., seven generations) but rather a probability distribution. As more information is compared, the TMRCA estimate becomes more refined.
When we count Time in the above TMRCA in generations it is important to understand how to count correctly. It is often assumed that each branch of two individuals is an equal number of generations. This is often not true. The correct way of counting generations between two individual is to start with the person tested and his father is 1, his father is two and so on to the common ancestor then keep counting down to the other person tested. This is called Degrees of Separation between two individuals or the Total number of births between two individuals. You divide Degrees by two to get equal generations per branch between two individuals. Most TMRCA calculators only accept or assume equal generations per branch between two individuals
MRCA = Most Recent Common Ancestor = In genetic genealogy, the Most Recent Common Ancestor (MRCA) is the ancestor shared most recently between two individuals.
GD = Genetic Distance = Genetic Distance is the number of differences, or mutations, between two sets of results. A genetic distance of zero means there are no differences in the results being compared against one another, i.e., an exact match. This is the meaning when comparing Y-chromosome DNA or mitochondrial DNA.
CI = Confidence Interval = This is the Statistical Confidence Interval between a fact. Example; a date is given in years say 1000 years, but it could be higher or lower. So the CI is written at 95% probability the date could be between 1300 to 850 years.
ybp = years before present = The number of years before the present date, the current genetic date used is 1950, so 1950 minus ybp = equal to the date in history. i.e. 1950 - 1100 ybp = 850 AD
STR = A short DNA motif (pattern) repeated in tandem. ATGC repeated eleven times would give the marker a value or allele of 11.
SNP = A single nucleotide polymorphism (SNP) is a change in your DNA code at a specific point.
https://www.familytreedna.com/learn/glossary/
Some Abbreviations and what they Mean:
EKA = Earliest Known Ancestor = The Earliest or most distant from you Ancestor, see MDKA.
MDKA = Most Distant Known Ancestor = Your most distant known ancestor (MDKA) is the furthest person who you have documented on a specific genealogical line. In genetic genealogy, it usually refers to someone on a direct maternal line (the mother, her mother, her mother’s mother, etc.) or on a direct paternal line (the father, his father, his father’s father, etc.).
TMRCA = Time to the Most Recent Common Ancestor = The amount of time or number of generations since individuals have shared a common ancestor. Since mutations occur at random, the estimate of the TMRCA is not an exact number (i.e., seven generations) but rather a probability distribution. As more information is compared, the TMRCA estimate becomes more refined.
When we count Time in the above TMRCA in generations it is important to understand how to count correctly. It is often assumed that each branch of two individuals is an equal number of generations. This is often not true. The correct way of counting generations between two individual is to start with the person tested and his father is 1, his father is two and so on to the common ancestor then keep counting down to the other person tested. This is called Degrees of Separation between two individuals or the Total number of births between two individuals. You divide Degrees by two to get equal generations per branch between two individuals. Most TMRCA calculators only accept or assume equal generations per branch between two individuals
MRCA = Most Recent Common Ancestor = In genetic genealogy, the Most Recent Common Ancestor (MRCA) is the ancestor shared most recently between two individuals.
GD = Genetic Distance = Genetic Distance is the number of differences, or mutations, between two sets of results. A genetic distance of zero means there are no differences in the results being compared against one another, i.e., an exact match. This is the meaning when comparing Y-chromosome DNA or mitochondrial DNA.
CI = Confidence Interval = This is the Statistical Confidence Interval between a fact. Example; a date is given in years say 1000 years, but it could be higher or lower. So the CI is written at 95% probability the date could be between 1300 to 850 years.
ybp = years before present = The number of years before the present date, the current genetic date used is 1950, so 1950 minus ybp = equal to the date in history. i.e. 1950 - 1100 ybp = 850 AD
STR = A short DNA motif (pattern) repeated in tandem. ATGC repeated eleven times would give the marker a value or allele of 11.
SNP = A single nucleotide polymorphism (SNP) is a change in your DNA code at a specific point.