Debbie Kennett 🧬🌳
@debbiekennett.bsky.social
DNA, genetic genealogy, family history. forensics. Honorary Research Fellow at UCL. All views my own.
Reposted by Debbie Kennett 🧬🌳
Great work by Harel Ismach, a student in my group, who has led the data analysis. Thanks to collaborators @gilig.bsky.social and @debbiekennett.bsky.social. The register data was made available by Israel's Central Bureau of Statistics.
August 12, 2026 at 8:18 PM
Great work by Harel Ismach, a student in my group, who has led the data analysis. Thanks to collaborators @gilig.bsky.social and @debbiekennett.bsky.social. The register data was made available by Israel's Central Bureau of Statistics.
Reposted by Debbie Kennett 🧬🌳
Nevertheless, our results are important because they apply to genealogical data *already accessible* to law enforcement in many countries, without relying on commercial providers.
Our results should inform regulators and practitioners of FIGG, as well as quantify biobank privacy risks.
10/10
Our results should inform regulators and practitioners of FIGG, as well as quantify biobank privacy risks.
10/10
August 12, 2026 at 8:18 PM
Nevertheless, our results are important because they apply to genealogical data *already accessible* to law enforcement in many countries, without relying on commercial providers.
Our results should inform regulators and practitioners of FIGG, as well as quantify biobank privacy risks.
10/10
Our results should inform regulators and practitioners of FIGG, as well as quantify biobank privacy risks.
10/10
Reposted by Debbie Kennett 🧬🌳
Key limitations:
* Finding a match does not guarantee identification
* Many relatives missed because of the limited time depth of the register
* Data errors (clerical, adoption, non-paternity, gamete donation, relationship misclassification, MZ twins)
* Generalizability to other countries
9/10
* Finding a match does not guarantee identification
* Many relatives missed because of the limited time depth of the register
* Data errors (clerical, adoption, non-paternity, gamete donation, relationship misclassification, MZ twins)
* Generalizability to other countries
9/10
August 12, 2026 at 8:18 PM
Key limitations:
* Finding a match does not guarantee identification
* Many relatives missed because of the limited time depth of the register
* Data errors (clerical, adoption, non-paternity, gamete donation, relationship misclassification, MZ twins)
* Generalizability to other countries
9/10
* Finding a match does not guarantee identification
* Many relatives missed because of the limited time depth of the register
* Data errors (clerical, adoption, non-paternity, gamete donation, relationship misclassification, MZ twins)
* Generalizability to other countries
9/10
Reposted by Debbie Kennett 🧬🌳
What is the probability of having *two* (or more) relatives in the database?
This is important, as it is often the intersection of the family trees of multiple matches that leads to identification.
The match rate naturally decreases, although not as much for the very large databases.
8/10
This is important, as it is often the intersection of the family trees of multiple matches that leads to identification.
The match rate naturally decreases, although not as much for the very large databases.
8/10
August 12, 2026 at 8:18 PM
What is the probability of having *two* (or more) relatives in the database?
This is important, as it is often the intersection of the family trees of multiple matches that leads to identification.
The match rate naturally decreases, although not as much for the very large databases.
8/10
This is important, as it is often the intersection of the family trees of multiple matches that leads to identification.
The match rate naturally decreases, although not as much for the very large databases.
8/10
Reposted by Debbie Kennett 🧬🌳
Unexpectedly, the match rate barely increases beyond 5th-degree (2nd cousins).
This is probably because the common ancestors of third cousins usually lived before the country's foundation.
Implication: whenever relatives are found in the database, they are usually not too distant.
7/10
This is probably because the common ancestors of third cousins usually lived before the country's foundation.
Implication: whenever relatives are found in the database, they are usually not too distant.
7/10
August 12, 2026 at 8:18 PM
Unexpectedly, the match rate barely increases beyond 5th-degree (2nd cousins).
This is probably because the common ancestors of third cousins usually lived before the country's foundation.
Implication: whenever relatives are found in the database, they are usually not too distant.
7/10
This is probably because the common ancestors of third cousins usually lived before the country's foundation.
Implication: whenever relatives are found in the database, they are usually not too distant.
7/10
Reposted by Debbie Kennett 🧬🌳
Results:
The match rate is the proportion of people with at least one relative (a "match") in the database.
For a database covering 1% of the country, the match rate is ~25%. For a database covering 10% of the country, the rate is 68%.
6/10
The match rate is the proportion of people with at least one relative (a "match") in the database.
For a database covering 1% of the country, the match rate is ~25%. For a database covering 10% of the country, the rate is 68%.
6/10
August 12, 2026 at 8:18 PM
Results:
The match rate is the proportion of people with at least one relative (a "match") in the database.
For a database covering 1% of the country, the match rate is ~25%. For a database covering 10% of the country, the rate is 68%.
6/10
The match rate is the proportion of people with at least one relative (a "match") in the database.
For a database covering 1% of the country, the match rate is ~25%. For a database covering 10% of the country, the rate is 68%.
6/10
Reposted by Debbie Kennett 🧬🌳
FIGG simulation:
We designated a random subset of the population as the "database".
For each person in the database, we used the register to track all of their relatives up to 7th degree (eg, 3rd cousins). This gave us the list of people who would have one or more relatives in the database.
5/10
We designated a random subset of the population as the "database".
For each person in the database, we used the register to track all of their relatives up to 7th degree (eg, 3rd cousins). This gave us the list of people who would have one or more relatives in the database.
5/10
August 12, 2026 at 8:18 PM
FIGG simulation:
We designated a random subset of the population as the "database".
For each person in the database, we used the register to track all of their relatives up to 7th degree (eg, 3rd cousins). This gave us the list of people who would have one or more relatives in the database.
5/10
We designated a random subset of the population as the "database".
For each person in the database, we used the register to track all of their relatives up to 7th degree (eg, 3rd cousins). This gave us the list of people who would have one or more relatives in the database.
5/10
Reposted by Debbie Kennett 🧬🌳
Data:
We used the entire Israeli national population register, documenting all parent-child relationships in all present and past citizens.
After QC, the dataset covered 12.5 million people, among them 10.4 million alive.
Summary stats look reasonable.
4/10
We used the entire Israeli national population register, documenting all parent-child relationships in all present and past citizens.
After QC, the dataset covered 12.5 million people, among them 10.4 million alive.
Summary stats look reasonable.
4/10
August 12, 2026 at 8:18 PM
Data:
We used the entire Israeli national population register, documenting all parent-child relationships in all present and past citizens.
After QC, the dataset covered 12.5 million people, among them 10.4 million alive.
Summary stats look reasonable.
4/10
We used the entire Israeli national population register, documenting all parent-child relationships in all present and past citizens.
After QC, the dataset covered 12.5 million people, among them 10.4 million alive.
Summary stats look reasonable.
4/10
Reposted by Debbie Kennett 🧬🌳
Our research question:
Given a genomic database covering x% of the population of a country, what is the probability that a target person has one or more relatives in the database?
Particularly, we focus on relatives from whom the target can be traced using available genealogical data.
3/10
Given a genomic database covering x% of the population of a country, what is the probability that a target person has one or more relatives in the database?
Particularly, we focus on relatives from whom the target can be traced using available genealogical data.
3/10
August 12, 2026 at 8:18 PM
Our research question:
Given a genomic database covering x% of the population of a country, what is the probability that a target person has one or more relatives in the database?
Particularly, we focus on relatives from whom the target can be traced using available genealogical data.
3/10
Given a genomic database covering x% of the population of a country, what is the probability that a target person has one or more relatives in the database?
Particularly, we focus on relatives from whom the target can be traced using available genealogical data.
3/10
Reposted by Debbie Kennett 🧬🌳
In forensic investigative genetic genealogy (FIGG), law enforcement people upload the DNA of an unknown person (a criminal or unidentified remains) to a consumer genomics database (eg FTDNA), find relatives, and intersect their family trees until reaching an identification.
2/10
2/10
August 12, 2026 at 8:18 PM
In forensic investigative genetic genealogy (FIGG), law enforcement people upload the DNA of an unknown person (a criminal or unidentified remains) to a consumer genomics database (eg FTDNA), find relatives, and intersect their family trees until reaching an identification.
2/10
2/10
The DNA testing has always had to be verified by standard forensic testing using STRs. It's the use of the Ancestry records, family trees and tree-building platforms that law enforcement want access to. The terms and conditions have been ambiguous in this regard.
December 12, 2025 at 1:59 PM
The DNA testing has always had to be verified by standard forensic testing using STRs. It's the use of the Ancestry records, family trees and tree-building platforms that law enforcement want access to. The terms and conditions have been ambiguous in this regard.
If you've not already done so, it's well worth watching the ITV documentary Lucy Letby: Beyond Reasonable Doubt. It's now available on YouTube: youtu.be/UohWz9L6PTs?...
Lucy Letby: Beyond Reasonable Doubt? | ITV
YouTube video by ITV Real Life Stories
youtu.be
December 5, 2025 at 4:59 PM
If you've not already done so, it's well worth watching the ITV documentary Lucy Letby: Beyond Reasonable Doubt. It's now available on YouTube: youtu.be/UohWz9L6PTs?...
They downgraded the unit when she was removed so they are no longer dealing with very vulnerable premature babies.
December 2, 2025 at 5:09 PM
They downgraded the unit when she was removed so they are no longer dealing with very vulnerable premature babies.