New Family History Research eBook: Save 50%!   Get Now →

How to Find Unknown Siblings

If you know very little about your family history, you might want to know how to find unknown siblings. In this article, we'll show you how to find unknown siblings using DNA testing and other tools.

The image of two parents and several kids is considered the ideal in society, it’s clean, uncomplicated and there’s very little to question about the family. This is not always going to be the case in life, however, and certainly has not been so historically.

Ancestry is Our Top Recommendation

If you love genealogy and family history research, then you must know Ancestry. They are the best way to discover the rich stories of your family!

With over 30 billion (seriously!) records in their database, you can research your family and discover amazing details you may never have known about your ancestors.

With a 14-day free trial, it's very easy to get started and discover your past!

Get Started →

There are many people who know very little about their family including myself at one point in my life, but more on that later. There are people who have been adopted or have been abandoned by one of their parents and who really do not know much about who they are and what family they may have.

This is when unknown siblings may come into the picture as a possibility. Separated from one or both of our parents if they are still living there is a chance that they had more children. We may even have been told that we have a half brother or sister out there somewhere.

Test Your DNA to Find Missing Family

As the child of an extramarital affair I have for most of my life been aware that I have a half-brother and three half-sisters who I have never met. They likely do not even know about me but I do know about them and have even seen pictures of them.

The reason I mention this is that as an AncestryDNA test taker if any of those half-siblings were to test or perhaps one of their children tested, they may be in for a shock. I would likely match them as an unknown half-sibling or in the case of their children an unknown half-uncle.

I have made the conscious choice not to interfere in their lives or reach out due to the nature of my birth but if this were to happen that is beyond my control. This of course can be the case for a lot of unknown siblings out there.

People can be sitting there completely unaware that they have a sibling and that person may or may not know about them. It does take an element of luck to locate an unknown sibling through DNA because it does require that they decide to seek their genealogical DNA as well.

Reach Out to Close DNA Matches

You may not get lucky and find a sibling through DNA but you may be able to find out something from close cousin matches. The usual problem is that you are unsure who one of your parents were; this is what typically stands in your way. Using cousin matches, however, it may be possible to find out the names of your birth parents.

These cousins may even know what became of your parents and where they may be if they are still alive. This can be another good way to use DNA as a tool to locate potential unknown siblings.

Talk to Your Adoptive parents or Older Relatives

If you are trying to find out things regarding your parentage the first best source is of course your older relatives. This may be either blood relatives or your adoptive parents. They may know information that can help you in your search for your absent parent or parents.

The first step is to try and locate your parents and then from there determine if they had any other children.


Contact Your State

If you are adopted and are trying to seek your birth parents and any siblings you may have one of the best places to start is in the State of your birth. It will depend on adoption laws but in some states once you reach a certain age you can request information regarding your birth parents.

If you can locate information regarding your birth parents it may be possible to find out if you have any half-siblings as well.


Build Your Family Tree

If you are fortunate you may know the name and some details regarding your parents and this may help you research them genealogically. If your father left the family, for example, you might be able to trace where he went, whether or not he remarried and also if he had any further children.

This can be a harder way to discover unknown siblings but with hard work and a little forensic genealogy, you might get some results.

Use Social Media

This may seem a little crazy but you can actually locate family through social media especially if you know some basic biographical information. I myself stumbled on some nieces of my father while trying to ask around for information regarding my paternal grandparents.

We live in a very connected world and if you have some idea of who your biological parents are they may be on social media. This may of course lead you to any children they had who would be your half-sibling.


We do need to understand though that even if we manage to locate an unknown sibling there is always a risk that they will not want contact with us. We may be elated at the prospect but for them, our very existence may be the sign of something negative in their family life.

It can be a difficult decision not to reach out to a sibling, I can certainly attest to that. As important as this may be to your life you must understand that their life and happiness also matter. Tread carefully in your search for unknown siblings and try to be understanding if they choose not to make contact with you.


There may be more people out there who have unknown siblings than you might think. As a genealogist, I have encountered it often and even have it in my own family. There are ways that you might come across an unknown sibling by accident.

If you suspect you may have unknown siblings there are also ways that your research can help you find out. The key of course is knowing who your parents are or were. This can be a scary path to go down but sometimes the rewards make it worthwhile.

Neil Edwards

Neil Edwards

Genealogist and family-tree research specialist

Neil was born in Shropshire, England surrounded by centuries of living history. His interest in the past has been a lifelong passion leading to undergraduate degrees in both Economic History & Geography and History & Politics.

This interest in history quickly translated to family history when he moved to the U.S. in 2010. It was here that he began working on his own family tree as well as that of his American wife. That research allowed him to gain a wealth of experience working with both U.S. and European genealogical documents and studying their best uses in researching family history.

Following 9 years of honing his genealogical research skills, Neil was proud to have earned a certificate in Genealogical Research from Boston University in late 2019. Neil also took part in the research process for a Duke University study into the families of 19th Century UK Members of Parliament.