ISSN 10227954, Russian Journal of Genetics, 2011, Vol. 47, No. 11, pp. 1288–1306. © Pleiades Publishing, Inc., 2011.
Original Russian Text © E.Ya. Tetushkin, 2011, published in Genetika, 2011, Vol. 47, No.11, pp. 1451–1472.
Genealogy is among the sciences that have had a sig
nificant impact on genetics, which borrowed from them
methods of pedigree analysis. However, until the late 20th
century, these disciplines practically did not interact.
Their first contact, which resulted in the appearance of
genetic, or molecular, genealogy, dates to the turn of the
21st century [1–5]. To date, other associations between
genetics and genealogy are beginning to appear.
Traditional genealogy is a supplementary historical
discipline studying pedigrees. However, genetics, from its
own standpoint, also studies pedigrees. Investigating its
specific problems, genetics made a significant, though
specialized, contribution to the description and analysis
of these subjects of genealogy. What has contributed and
can contribute genetics to the development of genealogy?
And vice versa, what are and will be the gains of genetics
from contacts with genealogy? What are the perspectives
of interaction of these sciences in the postgenomic era?
LAWS OF GENEALOGY
AND HUMAN GENETICS
In the early 20th century, the prominent Russian
genealogist L.M. Savëlov stated in his lecture course:
Genetic Aspects of Genealogy
E. Ya. Tetushkin
Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow, 119991 Russia;
Received March 3, 2011
—The supplementary historical discipline genealogy is also a supplementary genetic discipline. In its for
mation, genetics borrowed from genealogy some methods of pedigree analysis. In the 21th century, it started receiv
ing contribution from computeraided genealogy and genetic (molecular) genealogy. The former provides novel
tools for genetics, while the latter, which employing genetic methods, enriches genetics with new evidence. Gene
alogists formulated three main laws of genealogy: the law of three generations, the law of doubling the ancestry
number, and the law of declining ancestry. The significance and meaning of these laws can be fully understood only
in light of genetics. For instance, a controversy between the exponential growth of the number of ancestors of an
individual, i.e., the law of doubling the ancestry number, and the limited number of the humankind is explained by
the presence of weak inbreeding because of sibs’ interference; the latter causes the pedigrees’ collapse, i.e., explains
also the law of diminishing ancestry number. Mathematic modeling of pedigrees’ collapse presented in a number
of studies showed that the number of ancestors of each individual attains maximum in a particular generation
ancestry saturated generation
. All representatives of this and preceding generation that left progeny are com
mon ancestors of all current members of the population. In subdivided populations, these generations are more
ancient than in panmictic ones, whereas in small isolates and social strata with limited numbers of partners, they
are younger. The genealogical law of three generations, according to which each hundred years contain on average
three generation intervals, holds for generation lengths for Ychromosomal DNA typically equal to 31–32 years;
for autosomal and mtDNA, this time is somewhat shorter. Moving along ascending lines, the number of genetically
effective ancestors transmitting their DNA fragments to descendants increases far slower than the number of com
mon ancestors, because the time to the nearest common ancestor is proportional to
, and the time to genet
ically effective ancestor, to
is the population size. In relatively young populations, the number of genet
ically effective ancestors does not exceed the number of recombination hot spots, which is equal to 25 000–50000.
In ancient African populations with weaker linkage disequilibrium, their number may be higher. In genealogy, the
degree of kinship is measured by the number of births separating the individuals under comparison, and in genetics,
by Wright’s coefficients of relationship (
). Genetic frames of a “large family” are limited by the average genomic
differences among the members of the human population, which constitute approximately 0.1%. Conventionally
it can be assumed that it is limited by relatives, associated with the members of the given nuclear family by the 7th
degree of relatedness (
.78%). However, in the course of the HapMap project it was established that 10–30%
of pairs of individuals from the same population have at least one common genome region, which they inherited
from a recent common ancestor. A nuclear family, if it is not consanguinous, unites two lineages, and indirectly, a
multitude of them, constituting a “suprafamily” equivalent to a population. Some problems of genealogy and
related historical issues can be resolved only with the help of genetics. These problems include identification of
“true” and “false” Rurikids and the problem of continuity of the Ychromosomal lineage of the Romanov dynasty.
On the other hand, computeraided genealogy and molecular genealogy seem to be promising in resolving genetic
problems connected to recombination and coalescence of genomic regions.
THEORETICAL ARTICLES AND REVIEWS