The vocabulary of family history, defined by what it means in practice rather than in the abstract. If a term here decides how you read a record or a DNA match, that is what the entry explains.
The plain-text file format genealogy programs use to exchange data. A GEDCOM file (.ged) stores people, families, events and notes as numbered levels and four-letter tags, so 0 @I1@ INDI opens an individual record and 1 BIRT nested beneath it opens their birth event. It is the reason you are not locked into one program: almost every genealogy application can read and write it. AncestorOS imports and exports GEDCOM 5.5.1.
5.5.1 was published in 1999 and is still what nearly every program reads and writes, which is why it remains the safe choice for moving a tree between applications. GEDCOM 7.0 arrived in 2021 with UTF-8 as the only permitted encoding and a cleaner treatment of media, but support across the industry is still partial. If you are exporting a tree to give to someone else, 5.5.1 is the version most likely to open correctly on the other end.
A character encoding used by older GEDCOM files to represent accented letters. ANSEL stores the accent before the letter it modifies, the opposite of Unicode, so software that reads an ANSEL file as plain UTF-8 renders Björn as Bj̈orn or drops the diacritic altogether. If an imported tree shows scrambled or accent-stripped characters in Scandinavian, German, Polish or French surnames, an undetected ANSEL file is the usual cause.
The unit used to measure how much DNA two people share. A centimorgan measures genetic linkage rather than physical length: it is the distance over which there is roughly a one percent chance of recombination in a single generation. More shared centimorgans means a closer relationship. As rough anchors, full siblings share around 2,600 cM, a grandparent or half sibling around 1,700 cM, an aunt or uncle around 1,750 cM, and first cousins around 866 cM. Ranges overlap, so a single number narrows the possibilities without settling them.
Repeated intermarriage within a closed population over many generations, common in Ashkenazi Jewish, Acadian, Amish, Sabbatarian and many island and colonial communities. Endogamy inflates shared centimorgan totals, so two people from an endogamous population can share as much DNA as second cousins while their actual common ancestor is far more distant. Standard cM-to-relationship tables systematically overestimate closeness in these populations.
What happens when the same ancestor occupies more than one position in a tree because relatives married one another. Every tree collapses eventually, since the theoretical number of ancestors doubles each generation and quickly exceeds the population that existed. Practically, it means an ancestor can be both your great-great-grandfather on one line and your great-great-great-grandfather on another.
Establishing that a shared DNA segment came from a particular common ancestor by showing that three or more people all share the same segment, at the same chromosome position, and all descend from that ancestor. Two people sharing a segment only proves they are related somehow. Triangulation is what attaches the segment to a specific couple in the tree.
The nearest ancestor from whom two people both descend. Naming the MRCA is the usual goal of working a DNA match: it converts an anonymous name and a centimorgan figure into a defined position in your tree.
A clustering technique published by Dana Leeds that sorts DNA matches into four colour groups, which in a straightforward case correspond to the four grandparent lines. Matches are listed in a spreadsheet and each is coloured according to which other matches it shares. It works best on second to fourth cousins and breaks down under endogamy, where matches belong to several clusters at once.
A phonetic index that codes a surname by how it sounds, so that spelling variants file together. A Soundex code is the first letter followed by three digits: Strauss, Straus and Strausz all code to S362. The US census indexes for 1880 through 1920 were built on Soundex, which is why searching them by exact spelling misses records that a Soundex search finds. AncestorOS uses Soundex, combined with edit distance, to detect probable duplicate people.
The area assigned to a single census enumerator, and the unit census records are physically organised by. When an index fails you, knowing the enumeration district lets you read the census page by page for the neighbourhood rather than searching by name at all, which is often the only way to find a badly transcribed family.
Birth, marriage, divorce and death records created by a civil authority, as distinct from church registers of the same events. Availability varies enormously by jurisdiction: many US states did not require statewide registration until the early twentieth century, so before that the church record is frequently the only one that exists.
The two stages of United States naturalization. The declaration of intention, or first papers, renounced allegiance to the former sovereign and could be filed soon after arrival. The petition, or second papers, came after a residency period. For genealogy the declaration is often the more valuable of the two, because post-1906 forms record the exact birth date and birthplace, the ship, and the date of arrival.
Britain and its colonies began the legal year on 25 March until the calendar reform of 1752, so a date between 1 January and 24 March fell in what contemporaries called one year and we would call the next. Such dates are written with both, as in 12 February 1699/1700. Reading one of these as a single year misplaces the event by twelve months, and the error propagates through every calculated age in the tree. AncestorOS preserves dual-dated years on import.
The standard way of numbering ancestors. The subject is 1, and for any person numbered n the father is 2n and the mother is 2n+1. So 2 and 3 are the parents, 4 through 7 the grandparents, 8 through 15 the great-grandparents. Every man in the chart carries an even number and every woman an odd one, except the subject. The scheme lets you name a position in a pedigree unambiguously without drawing it, and it is what the AncestorOS fan chart uses internally.
The two conventional layouts for a descendant report in American genealogical publishing. Register format, from the New England Historical and Genealogical Register, numbers only those children whose lines are carried forward. NGSQ format, from the National Genealogical Society Quarterly, numbers every child and marks the ones continued with a plus sign. Both are correct; journals simply specify which they expect.
Anyone descended from your ancestors who is not in your direct line: siblings, aunts, uncles, cousins, nieces and nephews. Research that stalls on a direct ancestor very often moves again through collateral lines, because the record that names a parent may sit in a sibling's marriage or probate file rather than your own ancestor's.
The generational offset between two cousins. Cousins of the same generation are first, second or third cousins with nothing removed. Each generation of difference adds one remove, so your first cousin's child is your first cousin once removed. Degree counts how far back the common ancestor is; removal counts how unevenly the two of you descend from them.
The five-part benchmark defined by the Board for Certification of Genealogists for when a conclusion may be called proved: reasonably exhaustive research; complete and accurate source citations; thorough analysis and correlation of the evidence; resolution of any conflicting evidence; and a soundly reasoned, coherently written conclusion. It is a standard for the reasoning, not a threshold number of sources, and all five elements have to hold.
Elizabeth Shown Mills's reference work, and the de facto citation standard for American genealogy. It defines three forms for every source: the source list entry for a bibliography, the first reference note giving full detail at first use, and the subsequent short form for later references to the same source. AncestorOS ships 14 citation templates across 11 record categories, each producing all three forms.
A judgement about the informant, not the document. Information is primary when it came from someone with firsthand knowledge of the event, and secondary when it came from someone reporting what they were told. A death certificate is a single document carrying both: the date and place of death are primary, while the deceased's parents' names, supplied by a grieving relative, are secondary and are wrong surprisingly often.
A judgement about the record, not the informant. An original source is the first recording of the information. A derivative is anything produced from it afterwards: a transcript, an abstract, an index, a database entry. Every derivation is an opportunity for a name to be misread, so a conclusion resting on an index entry is weaker than the same conclusion resting on the image it indexes.
A judgement about how the information answers your question. Direct evidence answers it on its own, as a birth record naming the father does. Indirect evidence answers it only in combination with other evidence, as a land sale reciting an inherited share might. Negative evidence is the meaningful absence of something: a man missing from a tax list he should appear on is evidence he had left or died.
The point at which a line stops moving because the records that would carry it further have not been found or do not survive. Most brick walls turn out to be an untested assumption rather than an absence of records, which is why the standard advice is to widen into collateral relatives and neighbours, and to re-read what you already have.
AncestorOS builds these standards in: Ahnentafel-numbered fan charts, Evidence Explained citation templates, Soundex duplicate detection, and GEDCOM 5.5.1 import that reads ANSEL and dual-dated years correctly.
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