In genealogy, the male lineage is traced unambiguously using the Y chromosome because it is only passed down from the father to son. The male-specific portion of the Y-chromosome (MSY) contain an accumulation of mutations throughout time and all individuals carrying a Y chromosome are related through a single XY ancestor who (likely) lived around 300,000 years ago. There are mainly two principal types of tests, haplogroup test based on Single-Nucleotide Polymorphisms (SNPs) and haplotype test based on Short Tandem Repeats (STRs).
Haplogroup test (SNP):
- Builds the Y-DNA phylogenetic tree, refer to: Phylogenetic Trees >>
- The number of mutations separating individuals can be translated into a time to most recent common ancestor (TMRCA)
- Provides for a terminal haplogroup closer to current date (in widely tested haplogroups this test has a low FAR-value).
Haplotype test (STR):
- Summing a genetic difference between two sets of Y-STR alleles
- Mutates faster than SNP’s, but do not account well for back and parallel mutations
- Does NOT provide for a terminal haplogroup (rather a basic haplogroup with a high FAR-value)
Note: when ordering an haplotype test based on STR’s, e.g. FTDNA Y-DNA37 or Y-DNA111 only a basic haplogroup will be defined. Many testers get dissapointed when their result does not provide them with a haplogroup based on a sequenced SNP test.