I want to know the blood relationship with a deceased person!

Rewritten: November 9, 2024

This article explains in detail how to prove a blood relationship with a deceased person through DNA testing, covering the types of samples that can be used (extracted teeth, umbilical cord, hair, pathology tissue, hats) and their precautions, as well as the difference between private and legal testing.

Obon is one occasion to remember the deceased

Many people probably spent a busy time during Obon, visiting graves to remember ancestors and deceased loved ones, and gathering with relatives to show off grandchildren. In Japan, Obon has long been regarded as the period when the spirits of the deceased return home, and it is also an important occasion to reconsider family and blood ties.

However, while remembering the deceased, sometimes surprising facts come to light. For example, it is not at all uncommon for previously unknown relatives to be discovered during the process of sorting through a deceased person's belongings, or for proof of a blood relationship to become necessary during inheritance procedures [ref:1]. In such situations, DNA testing draws attention as a means of objectively proving a blood relationship with the deceased.

DNA testing analyzes an individual's unique genetic information (DNA sequence) to scientifically establish a biological parent-child relationship or blood relationship between two people. When both parties are living, it is common to collect oral mucosa (oral epithelium) with a cotton swab, but when the person being tested has already passed away, a sample must be obtained by another method. This article explains in detail what kinds of samples can be used to prove a blood relationship with a deceased person and what points should be noted.

When it is necessary to prove a blood relationship with a deceased person

There are more situations than you might imagine where it becomes necessary to investigate a blood relationship with a deceased person. Typical cases include the following.

• Inheritance procedures: When family register documents proving the blood relationship with the deceased are incomplete, or when an unacknowledged child claims inheritance rights
• Receiving insurance benefits: Cases where the beneficiary of life insurance or death benefits is limited to blood relatives
• Correcting or confirming the family register: When the family register has been lost or destroyed due to war damage or disaster, and objective documentation of the blood relationship is needed
• Disputes among relatives: When the question "Are we really blood-related?" arises and proof is required as part of legal proceedings
• Identity verification: When confirming the blood relationship between an unidentified body from a disaster or accident and a family member [ref:2]

In these cases, when investigating a blood relationship with a deceased person, the samples used for testing are almost inevitably something other than oral epithelium. Once time has passed since a person's death, it is often difficult to submit samples such as a toothbrush or cigarette butts. So what should be submitted as a sample?

The basic mechanism of DNA testing

When investigating a blood relationship through DNA testing, a technique called STR (Short Tandem Repeat) analysis is mainly used. STRs are regions of DNA where short base sequences repeat, and the number of repetitions differs from person to person. In the case of a parent-child relationship, a child inherits half of each STR type from the father and half from the mother, so comparing multiple STR loci allows determination of a parent-child relationship with high accuracy [ref:3].

Mitochondrial DNA analysis is an effective method for investigating maternal blood relationships. Because mitochondrial DNA is inherited only from the mother, it can be used to trace the maternal line through grandmother, mother, child, and grandchild. Even with a sample such as hair, from which sufficient nuclear DNA cannot be obtained, mitochondrial DNA analysis can still be used to investigate maternal blood relationships [ref:4].

Samples other than oral epithelium that we can propose

Here we introduce samples other than oral epithelium that can be used for DNA testing to prove a blood relationship with a deceased person. Each sample has its own appropriate storage conditions and precautions, so please review the following carefully.

1. Extracted tooth

   Teeth are hard tissue, and because the DNA inside is relatively well protected from the external environment, they are one of the most useful samples for DNA testing. Dental pulp (the tissue inside the tooth) contains abundant DNA, and under appropriate conditions DNA can be extracted with a high probability of success. However, this applies only to teeth extracted before cremation. After cremation, the high temperatures completely break down the DNA, making it unusable for testing. Teeth that were extracted during dental treatment while the person was alive and kept in storage can also be used as a sample, depending on their condition.

2. Umbilical cord

   In Japan, there is a long-standing custom of carefully preserving the umbilical cord, and many households keep it in a paulownia wood box received from the maternity hospital at the time of birth. A dried specimen at least 3 cm in length is preferable. If properly dried and stored in a wooden storage box, even one that has been kept at room temperature for about 30 years can still be used as a sample. The umbilical cord is the tissue that connected the baby and the mother's body, and it contains the DNA of the fetus (the baby's side). Depending on the circumstances of the testing, it may not be possible to return the sample, so if you wish to have it returned, please let us know at the time of application.

3. Hair

   Hair is also a sample that can be used for DNA testing, but caution is needed. If the hair root is attached, extraction of nuclear DNA can be expected, allowing investigation of both paternal and maternal blood relationships. On the other hand, if the hair root is not attached, extracting nuclear DNA is extremely difficult, and only maternal blood relationships can be investigated using mitochondrial DNA analysis. If a hairbrush or comb among the deceased's belongings has hair caught in it, please check whether the hair roots are attached before consulting with us.

4. Pathology tissue stored at a medical institution

   Pathology tissue collected and stored during a visit to a medical institution can also be used as a sample for DNA testing. Examples include a portion of an organ removed during surgery or tissue collected through a biopsy. Such tissue is typically stored in a formalin-fixed or paraffin-embedded state. While formalin fixation and paraffin embedding can cause some degree of DNA damage, extraction and analysis of DNA may still be possible using specialized techniques. We recommend contacting the medical institution to check the storage status of the pathology tissue.

5. Hat

   The inside of a hat has skin cells (epithelial cells) attached that have flaked off from the wearer's scalp or forehead. DNA can be extracted from these cells for testing. However, the following conditions must be met.

   • It was worn only by the deceased (if worn by other people, DNA from multiple individuals would be mixed together)
   • It was stored away from direct sunlight (ultraviolet light damages DNA)
   • It has not been washed (washing would remove the attached cells and DNA)

Sample storage condition determines the success of DNA testing

As described above, there are various types of samples that can be used for DNA testing of a deceased person, but in every case, the storage condition of the sample greatly affects whether the testing succeeds. In general, DNA degrades due to environmental factors such as high temperature, high humidity, and ultraviolet light. For this reason, please pay attention to the following points.

Depending on the condition of the sample, DNA extraction may be difficult, or the accuracy of the test results may be affected. Therefore, we recommend consulting with us by phone or email before sending in a sample.

The difference between private testing and legal testing

DNA testing is broadly divided into two types: "private testing" and "legal testing." Legal testing is intended for use as evidence in courts and other public institutions, and requires that samples be collected according to strict procedures with a specialist staff member present [ref:1].

When the person being tested has already passed away, it is extremely difficult to have a specialist staff member present to collect oral epithelium, so legal testing cannot be performed. Our company only accepts private testing in such cases, but some courts do accept private testing reports as evidence. We recommend consulting with a judge or similar authority before applying with us.

The DNA testing process

DNA testing to investigate a blood relationship with a deceased person generally proceeds as follows.

1. Inquiry and consultation: First, please consult with us by phone or email about the type of sample and its storage condition.
2. Application: Once you have agreed to the testing content and cost, please formally apply.
3. Sending the sample: Please send the sample using the specified method.
4. DNA extraction and analysis: DNA is extracted from the sample and STR analysis or mitochondrial DNA analysis is performed.
5. Reporting the test results: Based on the analysis results, the presence or absence of a blood relationship is determined, and a report is prepared and delivered.

Feel free to contact us

If you are considering submitting an item other than those listed above, please feel free to contact us by phone or email. Depending on the type and storage condition of the sample, our specialist staff will carefully guide you on whether DNA extraction is possible and the likelihood of successful testing.

Proving a blood relationship with a deceased person plays an important role in inheritance and legal procedures. seeDNA Co., Ltd. is fully committed to helping you scientifically prove the bond with your loved one. If you have any questions, please feel free to contact us.

Frequently Asked Questions

Q1. Is DNA testing possible no matter how many years have passed since the person died?

A. It largely depends on the storage condition of the sample. For example, if an umbilical cord has been kept dry in a paulownia wood box, DNA extraction may be possible even after about 30 years. On the other hand, if it was stored in a hot, humid environment, DNA degradation may have progressed, making testing difficult in some cases. Please first consult with us about the condition of the sample.

Q2. Can DNA testing be done using cremated remains?

A. Cremation exposes remains to temperatures of 800-1200°C or higher, which completely breaks down the DNA. Therefore, DNA testing using cremated remains cannot generally be performed. When using a tooth as a sample, it must be one extracted before cremation.

Q3. Can testing still be done if the hair has no root attached?

A. Even hair without a root attached can be used to investigate a maternal blood relationship using mitochondrial DNA analysis. However, determining a paternal blood relationship or a father-child relationship requires STR analysis, which requires hair with the root attached or another type of sample.

Q4. Can the results of DNA testing to prove a blood relationship with a deceased person be used in court?

A. When the person being tested has already passed away, it is difficult to collect oral epithelium with a specialist staff member present, so our company only accepts this as private testing. However, some courts do accept private testing reports as evidence, so we recommend consulting with the presiding judge in advance.

Q5. Can items other than hats (such as scarves or pillowcases) also be used as samples?

A. In addition to hats, clothing and bedding that may have the deceased's skin cells or sweat attached can potentially be used as samples. However, they must meet conditions such as having been used only by the deceased, not having been washed, and having been stored away from direct sunlight. Whether an item can be used is determined on a case-by-case basis, so please feel free to contact us.

Q6. How long does DNA testing take?

A. The testing period varies depending on the type and condition of the sample, but results are typically provided within a few weeks of the sample's arrival. For special samples other than oral epithelium, additional time may be required for DNA extraction. Detailed timing will be explained at the time of application.