Reduce Research Hours by Utilizing X-DNA Matches

Today’s blog is written by guest blogger Rhonda Kevorkian, DNA Doe Project


Are you using all the clues of autosomal DNA? The X chromosome can play a crucial role in complementing autosomal DNA results. The unique inheritance pattern can provide valuable clues, eliminating lines as you build family trees saving valuable research time.


This research examines three case studies drawn from the portfolio of the DNA Doe Project. These cases serve as examples of how difficulties can be overcome and time can be saved by analyzing segments shared on the X chromosome.



Case #1

John Doe b. 1918-1943 

John Doe had a male DNA relative with whom he shared 386 centimorgans (cM) of autosomal DNA and 33 cM of X-DNA. Our research revealed that this relative was born in 1978. Taking into account the ages of John Doe and the DNA relative, it seemed likely that we were dealing with a relationship one or two generations removed. While the uncle/nephew relationship was a possibility, the presence of 33 cM of X-DNA indicated multiple recombination events. To narrow it down, we considered the possibility of a most recent common ancestor (MRCA) at the great-grandparent level of the DNA relative. This led us to focus on the maternal grandmother’s parents as the likely shared ancestors.


We constructed a family tree, tracing it back to the great-grandparent level of the DNA relative. This couple had 11 children, all of whom were older than John Doe’s age range and accounted for in existing records. However, our investigation didn’t stop there. We turned our attention to the female children of the great-grandparents and their descendants. Our diligent search paid off when we discovered that one of the daughters had a son who could not be recently accounted for.


With this promising lead in hand, we built the family tree for this candidate and uncovered shared common ancestors on all grandparent sides, connecting them to other DNA relatives in the match list. The evidence was compelling, and we reported our findings to the agency. It was confirmed that the candidate was indeed our John Doe.


Notably, the inclusion of X-DNA was instrumental in this case. It significantly expedited the identification process and saved valuable time. By analyzing X-DNA, we were able to focus our search on the maternal line, leading us to the ultimate breakthrough.


This case demonstrates the power of DNA analysis in unraveling complex family relationships. Through careful investigation, family tree construction, and the strategic use of X-DNA, we were able to reunite John Doe with his relatives. This success story underscores the importance of combining science and genealogy to solve mysteries and connect families.



Case #2

Jane Doe b. 1965-1980

Jane Doe shares a unique genetic connection with a male relative, characterized by 84.5 cM of autosomal DNA and a substantial 108.3 cM of X-DNA. Through research we have identified that this male relative was born in 1964, placing him in the same age bracket as or possibly older than Jane. We delve into the intriguing possibilities presented by this genetic information, shedding light on the potential relationships and uncovering the fascinating journey that ultimately led to the identification of Jane.


When we consider the extent of shared X-DNA and the knowledge that it passes from father to daughter without recombination, the large centimorgan total suggests that his mother likely inherited this X-DNA segment from her father, passing it on to him. Consequently, our family tree traces this lineage through his maternal great-grandparents.


Through triangulation involving two other DNA relatives with similar cM shares, we identify a likely 2nd cousin relationship. Starting with the MRCA couple, we trace the lineage downward, revealing a descendant who married into the male relative’s family, connecting our two genetic branches. This research leads us to the identification of a union couple close in age to Jane, raising strong suspicions that they may be her parents.


This couple had three daughters, one of whom remained unaccounted for. The lead was reported to the relevant agency and subsequently confirmed to be Jane, culminating in the successful identification of our subject.


The journey to unravel Jane Doe’s identity has been a fascinating one, filled with intricate genetic clues, probabilities, and careful genealogical research. Through shared cM analysis, X-DNA examination, and triangulation, we navigated a complex genetic maze, ultimately leading us to a long-lost relative and, with further investigation, to the confirmation of Jane’s identity.



Case #3

John Doe b. 1936-1956

In the intriguing case of John Doe, a web of familial connections and complex genetic data posed a formidable challenge. We’ll delve into the intricacies of this case, revealing how a combination of genetic analysis and astute genealogical investigation unveiled the truth.


John Doe’s genetic puzzle began with a shared 18 cM of DNA between his parents, as confirmed by GEDmatch’s ‘Are Your Parents Related’ (AYPR) tool. This anomaly strongly indicated the presence of a common ancestor couple on both sides of John Doe’s family tree, suggesting a phenomenon known as pedigree collapse.


To address this intriguing case, we embarked on a journey to identify the MRCAs and explore the intricate downlines, which were further complicated by multiple marriages between families. This phenomenon was particularly common in small towns where limited options for choosing spouses among neighboring families prevailed. Over generations, these intermarriages created a tangled web of potential pathways to our candidate.


Our breakthrough moment came when we discovered an X-DNA match with a male relative who shared 133.9 cM of autosomal DNA and 52.9 cM of X-DNA. Within this match’s family tree, several potential common ancestor couples emerged. The presence of X-DNA was instrumental as it indicated that the MRCA must be located on the X path of both males and within their maternal lines. Our research team employed a strategic approach, constructing downlines exclusively along the inheritance path. This eliminated many couples involved in multiple sibling marriages and allowed us to narrow our focus effectively. This approach significantly accelerated our progress, reducing the time required to identify a candidate by half.


With the added knowledge that a common ancestor existed on both parent lines, we were able to confidently report our candidate to the relevant agency. Subsequently, their identity was confirmed, concluding this intricate case.


John Doe’s complex genetic puzzle showcased the power of genetic analysis and strategic genealogical investigation. By leveraging X-DNA and narrowing our focus, we unraveled the intricate web of familial connections, ultimately leading to the identification and confirmation of our candidate. This case resolution offers hope in even the most challenging of circumstances.