Freedom of HGC08/P17
HUMAN GENETICS COMMISSION
Genetic Ancestry Testing
1. The purpose of this paper is to provide background to a possible draft
HGC statement on genetic ancestry testing (Annex A). The Commission is
asked to consider the issue of genetic ancestry testing and to consider a
draft HGC statement and provide comments.
Commissioners are invited to consider whether HGC should respond to
recent developments in this field and, if appropriate, to consider a draft
HGC statement on genetic ancestry testing and to offer comments
and/or amendments for the preparation of a final version.
2. Genetic ancestry testing is becoming increasingly popular amongst
consumers seeking information about their family histories, including the
geographical origins of their ancestors.
3. In February 2004, the HGC held an information-gathering meeting on the
topic of DNA-based genealogy in order to gain an understanding of the
current scientific basis, commercial activities and personal narratives in
relation to genealogy testing.
4. In October 2007, the internet-based company ancestry.co.uk launched a
DNA testing service to support its genealogy service. Many other internet-
based companies offering this type of service exist in the UK and
5. An analysis of some of the issues that are raised by genetic ancestry tests
was published in Science in October 2007 (Annex B). According to this
article, more than 460,000 people have purchased such tests in the past 6
years and interest in DNA-test based genealogy continues to rise.
6. In May 2008, the HGC was contacted by a senior researcher from
Computing Which? preparing an article on issues relevant to DNA testing
for genealogy purposes. The article was published in the July 2008 issue
of Computing Which? (Annex C).
7. The main issues associated with genetic ancestry testing are its scientific
constraints, the constraints this imposes on the interpretation of results,
how these results are presented to the consumer and the personal impact
HGC08/P17 – Page 1
the results might have on people taking the tests and their families, as well
as certain sociological consequences.
Scientific constraints of DNA ancestry testing
8. The most commonly offered analyses are Y chromosome tests and
mitochondrial DNA tests.
9. Y chromosome-based genetic genealogy involves testing for short tandem
repeats (STRs) and/or single nucleotide polymorphisms (SNPs). STR
sequences on the Y chromosome change frequently between generations
and therefore, in general, the more STRs are held in common the higher
the probability of a genetic relationship. By contrast, single nucleotide
polymorphisms occur with much less frequency and can therefore be
indicative of a shared progenitor. Used in combination, STR and SNP
analysis can provide a greater probability of common ancestry.
10. The sperm’s mitochondria are destroyed after fertilisation and
mitochondrial DNA can therefore be used as an indicator of maternal
ancestry. Mitochondrial DNA has a high mutation rate and genetic
ancestry analysis uses DNA markers in the hypervariable region.
11. One scientific constraint is that both Y chromosome analysis and
mitochondrial DNA analysis can only ever provide information about a
single common ancestor, i.e. the original provider of the Y chromosome or
mitochondria. It does not provide ancestral information encoded by a
person’s autosomal chromosomes.
12. Similarly, for both Y-chromosome and mitochondrial DNA analysis,
probable progenitor populations are identified by comparing the
individual’s DNA markers with known population databases. The
usefulness of the information gained from matching an individual’s DNA to
a given database therefore depends on the size and sample variety of the
database, which may also only include data from individuals living in a
small geographical area.
13. In conclusion, any interpretation of DNA based genealogy analysis has to
bear in mind the scientific constraints and the fact that any result will in
most cases only provide a measure of probability of ancestry.
Personal and familial issues
14. As well as trying to find out more about their historical ancestry, some
people may use these services in the hope of identifying contemporary
biological relatives. For example, some companies offer a facility that
allows the individual to search a database for matches with other users.
Whilst this may offer adopted or donor conceived people a way of finding
their biological parents, it may for some also provide unexpected news of
non-paternity and, for others, an unwelcome and unexpected intrusion of
HGC08/P17 – Page 2
15. There are also issues around data-sharing and consent. For example, the
Which article quotes one company sharing both the customers’ DNA
results and their name with others on the database by default, the
consumer would actively have to change their privacy settings in order to
opt out of the data-sharing.
16. DNA based genealogy is sometimes viewed as a harmless recreational
activity which presents little risk to the consumer. However, this perception
does not take into account the fact that many consumers use these tests
in order to find out more about their individual and/or ethnic identity. Any
incomplete or misguided interpretation of results therefore has the
potential to affect a person deeply. In some cases where the results are
unexpected or undesired, or contradict other traditions with which the
individual may have identified, the results may also cause distress.
17. Other concerns about impacts are the area of social policy. If a person
uses the information provided by a DNA based genealogy test as
confirmed proof of their racial or ethnic identify, it may affect how they
record their ethnicity on official documentation which could in turn have an
impact on ethnic equality monitoring. There can be financial consequences
and motives, too. In the United States, for example, the results obtained
from these tests have led individuals to financially support certain
communities in the developing world; others have taken the tests in order
to gain access to social welfare programmes.
18. Some of the other issues associated with commercial DNA based
genealogy services are the same as are relevant to other commercial
DNA-based tests. They include arrangements for providing consent,
quality assurance and scientific standards, sample storage conditions, and
security and accessibility of the database.
19. Some anthropologists have raised additional concerns over a possible loss
of consumer confidence in genetic tests and in genetic research more
generally. If consumers discover that they were not adequately informed
about the limitations of DNA based genealogy and perceive that they were
misled, they may develop a distrust of the medical research community.
Questions for discussion
20. The HGC is currently preparing further work on direct-to-consumer genetic
testing. The Commission has also prepared a draft statement of support to
the Scientific Advisory Committee on Nutrition’s statement on
‘nutrigenomics’ (to be discussed at this plenary, under Standing Items
paper number HGC08/P19). Commissioners may therefore wish to
HGC08/P17 – Page 3
o to what extent the issues presented by genealogy testing are
distinct from those raised by direct-to-consumer genetic testing
o whether provision of these tests in inappropriate circumstances
has the potential to cause harm to the consumer
o whether the issues presented by commercial DNA-based
genealogy services are of enough significance that although the
tests do not make health-related claims, they should be subject
to some form of regulation and whether they should therefore be
included in the work that HGC is planning on direct-to-consumer
o whether a statement on genetic ancestry tests should be
published on the HGC’s website in advance of HGC’s further
work on direct genetic testing
Commissioners are asked to consider and discuss the above questions. If it is
decided to proceed with the publication of a statement on genetic ancestry
testing on the HGC website, Commissioners are asked to provide comments
on the draft statement attached at Annex A.
Annex A – Draft HGC statement on genetic ancestry testing
Annex B – “The science and business of genetic ancestry testing” (Science,
Vol 318, pp 399-400 (19 Oct 2007), available at
Annex C – “Genetic defect” (Computing Which?, July 2008)
HGC08/P17 – Page 4
HGC08/P17 – ANNEX A
Draft HGC Statement on Genetic Ancestry Testing
Genetic ancestry testing is becoming increasingly popular amongst
consumers seeking information about their family histories including the
geographical origins of their ancestors.
In recent years, academic anthropologists have begun to use DNA technology
to study the history and structure of populations and to explore patterns of
migration and human genetic diversity. Increasingly, however, genetic
databases, which are compiled for purposes of studying population groups,
are also being used by commercial providers offering ancestry testing for
individuals. Such commercial DNA ancestry testing, in addition to having
scientific limitations which require careful interpretation of results, raises a
number of other issues of which consumers should be aware.
On the one hand, commercial genetic ancestry testing can be seen as just
one of the ways in which people try to make sense of their origins and family
history – a personally rewarding recreational activity. On the other hand, if not
interpreted in the right way, the results of such tests have the potential to
change an individual’s perception of their identity and therefore may present
more serious consequences for the individual, their relatives and for society
One scientific constraint is that both Y chromosome analysis and
mitochondrial DNA analysis, the most common types of test, can only ever
provide information about a single common ancestor, i.e. the original provider
of the Y chromosome or mitochondria. It does not provide ancestral
information encoded by a person’s other (autosomal) chromosomes.
Similarly, for both Y-chromosome and mitochondrial DNA analysis, probable
ancestral populations are identified by comparing the individual’s DNA
markers with known population databases. The usefulness of the information
gained from matching an individual’s DNA to a given database therefore
depends on the size and sample variety of the database, which may also only
include data from individuals living in a small geographical area.
Given these limitations, consumers should consider carefully their motivation
for undertaking DNA-based genealogy. The results that are provided will in
most cases only provide an incomplete picture of genetic ancestry. The
results may also have emotional consequences, especially for people who
may use them to answer fundamental questions of identity and ethnicity.
Some DNA-based genealogy services offer a facility that allows the individual
to search a database for matches with other users. It is important that
consumers are aware of the privacy implications of such data-sharing. Whilst
some results may come as a pleasant surprise, others might be unwanted
and/or unexpected, for example, it may reveal that a person’s presumed
parent is not their biological parent.
HGC08/P17 – Page 5
HGC08/P17 – ANNEX A
Important points to take into account, and questions to ask, when taking an
ancestry test are:
• There is a high level of genetic diversity within populations and
little evidence of distinct biological groups.
• There is not a strong relationship between an individual’s DNA
and their race or ethnicity (these are social rather than biological
• The tests cannot accurately say which part of the world a
person’s ancestors came from.
• Does the company provide enough information so that the
consumer can come to an informed decision on how
useful/informative the test is going to be?
• What is the company’s policy for storing DNA and what will
happen to the results (for example, will they be publicly available
and will they identify the individual)?
Some of the limitations of testing and the comparisons made with other
samples will diminish as more research is done. However, for the time being
the puzzle of our ancestry and origins is not going to be completely solved by
Beware the Gene Genies – Martin Richards (Education Guardian Feb 21
The Science and Business of Genetic Ancestry Testing – Bolnick et al
(Science Vol 318 Oct 2007)
Genes Direct (HGC, 2003) and More Genes Direct (HGC, 2007)
HGC08/P17 – Page 6