Remembering
Ancestors
By Paul VanRaden
©2025
Topics:
Displaying ancestors in a pedigree
Ancestry
origins from pedigree
Ancestry
regions from DNA
Finding
DNA matches for relatives
Predicting
traits
Data
sources
Relationships,
inbreeding, and heterosis
Conclusions
References
Displaying ancestors in a pedigree
At USDA we wrote programs to display ancestor information
from a database onto a screen beginning in 1993. Most pedigree displays become
very wide with many generations and then leave much empty space at the left for
the recent generations. The display style we invented lists standard data
fields such as birth date in one long column together. After those fields, each
generation indents only a few spaces more than the last, greatly reducing the
width and giving a vertical pedigree with one ancestor per row that can be
easily emailed or printed on standard paper. I used those ideas for my own
pedigree below. This style could be programmed to provide the same report for
any pedigree by pulling data from a database or an export file, but I had to
type this one by hand:
Ancestry origins from pedigree
People have wanted to know where their ancestors lived, how
long they lived, and stories about them since Biblical times. Often, historians
recorded only the all-male path from father to grandfather to great
grandfather, etc., or from father to son to grandson, etc. because family
names, property, and power were often inherited that way, such as with kings.
Many people even worship a father and a son but not a mother or a daughter. But
in this last century, females may own property, hold power, have equal rights
such as to vote, and deserve their history (herstory) told also. Hallelujah!
My nieces Hillary King and Andrea Sabaka found or stored
about 230 of my ancestors in a commercial database (ancestry.com) and added
many pictures and stories about their lives. We Americans had forgotten much of
this history, but our German cousins wrote a 100-page book about our VanRaden
ancestors and those families. Then I transferred the key fields into the
pedigree document above and used that to trace where our family’s DNA is from.
My sister Judy Winship thought of giving each generation a different color to
help see the connections. Humans will never get pedigrees as deep and accurate
as cattle because farmers gave cattle a 100-year head start and because cattle
generations take only 2-5 instead of 20-40 years.
Pedigree depth averages about 7 generations for me and my
sibs, 8 generations for our kids, and 9 for their kids. For 3 of my 4
grandparents, all 14 paths trace back to my 2nd or 3rd
great grandparents who immigrated to northwest IL from Germany around 1850. My
father’s ancestors were all from northwest Germany close to Netherlands and my
maternal grandmother’s were from southwest Germany
near Stuttgart and one from Frankfurt. Of my maternal grandfather’s ancestors,
94% trace to northeast U.S. states (CT, MA, NH, RI) and only 6% go back to my 7th
to 9th great grandparent immigrants from England. In the 1700s, most
New England colonists were from England and my ancestors’ last names sound
British, so my pedigree is 75% German, 2% British, and 23% probably British.
My genomic origins were 63% western Europe (45% northwest
Germany, 11% Netherlands, 7% southern Germany), 34% southeast England or
northwest Europe, 2% north Wales or northwest England, and 1% Czechia to the
east of Germany. My 11% from Netherlands makes sense since my paternal
ancestors lived just across the border and spoke the Low German (Plattdeutsch)
language common across northern Germany and northeast Netherlands.
The only surprise was 1% Czech DNA which is why we check our
DNA. Generally, a pedigree listing the former hometown of each immigrant
ancestor is more precise than a DNA test unless that immigrant had some earlier
ancestors from far away. But the DNA test more precisely estimated origins for
the 23% of my pedigree that ended in New England and did not trace back to
immigrants. My previous job at USDA included estimating genomic origins for
millions of cows. For cows or for dogs, scientists use DNA to check breeds
of origin instead of places of origin.
Finding DNA matches for relatives
DNA testing companies can find close relatives also tested by
that same company, and 25% of my DNA matches my niece Hillary’s DNA, as
expected. My highest other matches were 5-7% with 2 sons of my paternal
grandmother’s sisters and with 1 granddaughter of my maternal grandfather’s
brother. She is my second cousin, but Ancestry suggested her as a 1st
cousin once removed or half first cousin. Some relatives share more or fewer
DNA segments than average, like not always getting 11 heads and 11 tails when
flipping a coin 22 times. Each parent has 2 sets of chromosomes, and at each
location you get their DNA from their mother or their father, but not both.
Ancestry correctly guessed which relatives were on my Dad’s side or my Mom’s
side because my great grandparents each had many descendants to help sort the
DNA into individual chromosomes, a mathematical process called phasing.
Ancestor discovery for cows is much more accurate because we
have DNA from 10 generations of ancestor bulls and very complete and accurate
pedigrees for all bulls across the whole world. Future generations of humans
will have more of their ancestors’ DNA already analyzed. That will simplify the
process of connecting relatives because each next generation can just confirm
their direct relationship to their ancestors’ DNA instead of indirect
relationships to cousins’ DNA. Many dairy farmers across the world now trust
our programs to create pedigrees for their cows and calves using the DNA
matching system that my coworkers and I developed at USDA. Parent matching is
very easy, and already > 2 million unknown grandparents
and great grandparents were discovered by DNA and automatically added to
the global cow pedigree file.
Ancestry.com also predicted many traits as yes/no or high/low
and a few traits had high/average/low. For predictions of my traits, 28 seemed
correct but 19 seemed wrong. That may not be very accurate if one of the two
categories is much more frequent than the other. For example, if 15%
of people have freckles you could get 85% correct predictions by always
guessing no freckles with no data. Some Ancestry traits use markers known from
literature to have large effects but most traits use survey replies from their
DNA customers. Strangely, they did not predict height, which is highly
heritable and was the first trait that human geneticists studied in detail in 2010.
That study used almost the same genomic methods we developed at USDA and used
for predicting cow stature since 2008.
Predictions for 50 cattle traits each come with percent
reliability estimating how accurate they are expressed as a squared
correlation. The trait predictions are expressed using 2 or 3 decimal digits
instead of binary yes/no. Genetic effects can be estimated very precisely even
if the observed traits are predicted less well due to low heritability. Farmers
use the predicted traits to directly manage the current generation or to select
the next generation, and most cattle traits have known economic values.
Thus, farmers can easily profit from cattle DNA predictions available since
2008 and pedigree predictions since 1926. Human DNA tests are mostly for
entertainment. Trait predictions began much earlier at 23andMe, off and on since 2007
due to changes in regulations, than at Ancestry.com since 2018.
The technology to read DNA is almost
the same across many different species. For humans, several different companies
collect DNA samples and store pedigree data. Ancestry.com has sold over
28 million DNA tests as of 2025 and 23andMe sold 14 million DNA tests
as of 2024. The largest cattle DNA database begun by USDA and managed by the
Council on Dairy Cattle Breeding has over 11 million DNA tests as of
2025.
For humans, competing companies likely do not yet share
pedigree data. Even within Ancestry.com, their German database had pedigrees
for several older ancestors that were not in the American database. For dairy
cattle since 1995, Interbull in Sweden receives full
pedigrees from about 25 countries for all commercially available dairy bulls. Interbull then sends to each country a complete file of
combined and edited pedigrees from all the world’s bulls for several different
breeds. Dairy cattle breeders want to see the full global pedigrees because
most Holstein bulls have foreign
fathers or grandfathers. Cattle are not forced to stay within country
borders. Cows are one big, happy family across the whole world. Hallelujah!
Knowing names and locations of ancestors is not as
interesting as learning stories or seeing pictures from their lives. For
example, our German cousins documented the lives of our VanRaden ancestors that
we American descendants had forgotten:
Relationships, inbreeding, and heterosis
Inbreeding coefficients are very important in livestock
breeding because progeny may be less healthy if parents are too related. Most
humans are much less inbred than most livestock. I did not get either DNA or
pedigree estimates of inbreeding from Ancestry, but my pedigree inbreeding may
be 0 because I did not notice the same names among my maternal and paternal
ancestors. We could imagine finding 5 or 10 more generations of ancestry and
then my inbreeding coefficient might be a tiny bit above 0 but nothing to worry
about.
The pedigree methods
that quantify how inbred or how related any 2 individuals are to each other
were published in 1922 by geneticist Sewall Wright from the same USDA research
center where I worked. His parents were cousins which likely got him interested
in the topic. His example in paper was a cow pedigree, but his methods are now
used for all species. Then in 2008 I published DNA-based methods to
estimate how inbred and how related cows are to each other. Those methods are
now used for DNA predictions of traits for countless other species, but the DNA
relationships from most companies now use haplotypes instead of genotypes after
statistically separating the 2 sets of chromosomes into maternal vs. paternal
DNA.
People in the Americas might be a little less inbred than
people within Europe, Asia, or Africa whose ancestors all lived in the same
nation or small region of it. DNA can quantify those differences. For example,
my DNA may be a little more diverse than my father’s because 100% of his DNA
came from northwest Germany whereas I have 75% German and 25% British
ancestors. My mother may have lower DNA inbreeding than both of us because her
father had British DNA and her mother German DNA with even less chance of any
common ancestors. My daughter has no inbreeding and some positive heterosis
with a mixture of European and African DNA. Latin
Americans often have mixes of native American, European, and African DNA.
The term heterosis describes effects that cannot be traced by pedigrees when
the 2 parents have DNA from different populations that were separate for many
generations. Inbreeding
and heterosis are similar topics.
Genealogy was a hobby for millions of
people but was a big business for livestock breeders for more than a hundred
years after breeds were defined and trait data collection began. Large
databases allowed farmers and breeding companies to predict and to select for
traits they wanted livestock to have. Knowing about your pedigree and your DNA
is still mostly a hobby and a curiosity for humans but is beginning to be
useful for separating genetic from environmental causes in medical treatment.
Future generations may find services offered by genealogy companies more useful
or even get better DNA
than we got. Our genes have big effects on many of our traits, and better
understanding our DNA could improve everybody’s lives in the future.
References
Sewall
Wright, 1922. Coefficients of
inbreeding and relationship.
Discovering
ancestors and connecting relatives in large genomic databases - ScienceDirect
Fast
two-stage phasing of large-scale sequence data: The American Journal of Human
Genetics
Efficient methods to compute
genomic predictions - PubMed
Invited
Review: Reliability of genomic predictions for North American Holstein bulls -
ScienceDirect
How
Common Are Freckles? Global Statistics
Common SNPs explain a large
proportion of the heritability for human height | Nature Genetics
Timeline for 23andMe
DNA testing
Countries
Where AncestryDNA® is Available
Ancestry
Launches a New Take on Genetic Traits
How
We Develop Traits - Ancestry DNA
TraitsPredictionWhitePaper_042024
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