Siblings and I had our DNA tested shows they share father (who passed), but not me, How do I find my biological dad?

+15 votes
658 views DNA test, brother and sister match, only one living older relative that I will question, an older cousin says dad is "the milk man" really.
in Genealogy Help by Raymond Howell G2G Crew (910 points)

You might be interested in the recent book The Stranger in My Genes, by Bill Griffeth. It's a memoir about his shock at discovering from DNA that his father wasn't really his father, and his odyssey to find the true story.

thanks Ellen,  I will look at that, it does make me anxious, where to go/look
The book is being promoted and offered for sale by NEHGS on I believe Amazon is selling print and ebook editions, and I read a preview on the web, probably on Google.
Thank you so much.  I love a good read.  The book is available as inter-library loan to my local library.

3 Answers

+11 votes
A couple of suggestions.  First put the data on GENmatch. you'll get lots of matches and some may be large enough and from your home town to let you have a good idea about who it might be.  Second, get tested for you Y chrosome.  This will give you your biological father's line.  It may or may not be rare in the area you were born in.  You may very well have a surname to work with at any rate.
by Dave Dardinger G2G6 Pilot (407k points)
GEDmatch at It's free to use although some of their advanced tools need a $10/month fee. You can do a lot w/o them however.

And add your YDNA to Ysearch and join research groups on FtDNA that are studying the different types of YDNA.
Dave, you referred to GENmatch. Is that a typo? Did you mean to write That is the site that Rosemary explained. The suggestions from both Dave and Rosemary are good ones. Raymond, you will need to contact Family Tree DNA for a yDNA test. To start I would recommend that you take a yDNA 37 marker test.
I am on GEDmatch, I have to modify my tree to remove non-bio dad to up load data.  But what is testing for Y chromosome, how does that work, what will bio dad's line give me?


thank you Dave
Hi Raymond, The Ancestry test you took is an autosomal test (auDNA). When you match someone else's DNA you can tell approximately how far back the relationship might be by looking at how much shared auDNA you have. yDNA is a bit different. Women do not have a y Chromosome and only men can take a yDNA test. If your yDNA test shows that you match another man fairly closely (35, 36 or 37 markers out of 37) then you can be fairly certain that you share a paternal line ancestor (father/grandfather/great grandfather, etc) in a genealogical time frame. (It is valuable many generations further back than auDNA.) Because in our culture children generally take the surname of the father, IF you have a number of matches with men who all have the same surname, you will probably know the surname of your father. I wrote IF in capital letters intentionally. For various members of my family I have worked with these surnames: Smith, Wilson, and Stone. For Smith and Stone my male relatives had 10 or 12 matches each with the same surname, and the yDNA has been very helpful in working on tracking down the male line. My Wilson relative doesn't have any close yDNA matches and the more distant ones all have different surnames, not Wilson. As with any DNA test, it depends on whether or not other people related to you have also tested. So it's a bit of a long shot. It has a lot of potential for you if a male relative of your biological father has tested.

You wrote that you have uploaded your DNA test to I recommend that you put your GEDMatch ID on your WikiTree profile. Do you have any close matches there? If you do, that could save you the expense of a yDNA test.
Nice answer, Kay.  I would suggest 37 marker yDNA tests for both Raymond and his brother.  Tests should go on sale between Thanksgiving and Christmas.

Raymond should also transfer his Ancestry test results to FamilyTreeDNA ( and join the Howell DNA Project (
HOLEY MOLEY Kay, there is so much to learn/know, thanks for the advise and direction, I will look for the sale price at FamilyTree, I will also add my GEDmatch ID to my profile......WOW!!!!!!
Thanks for adding your GEDMatch ID to your WikiTree profile. On GEDMatch, in the 'Analyze your data' section on the right, select the first one: 'One to Many' Matches. That will give you a list of your matches, with your closest matches at the top of the list. It looks like you've uploaded your Ancestry kit twice, but if you look at the next three entries, with the same e-mail address, it looks like they're probably your second cousins (with whom you share great grandparents). You should definitely write to the person who manages those three kits and see if they can give you any clues to who your father might be. If I were you I would also contact the next three or four e-mail addresses on the list. Good luck!
Thank you Rosemary
Thanks Kay, I looked into the One to One matches and the next several are related one my mom's side, but I will look further down the list.


Hey Kay, I knew I had prior contact on here, don't know how I found this, but you gave gave great advise then, and now.

thanks again,

+4 votes
How exactly do you know you don't have the same Dad if your father is deceased?  Are you going by the estimates of shared chromosomes provided by AncestryDNA?  Are you saying you didn't match your siblings?   If you share a mother it will be useful to be able to isolate the segments coming from her side.  They should also put their data on GEDmatch too.
by Veronica Williams G2G6 Pilot (142k points)
Raymond didn't say how he knows, but he doesn't need a living father to figure this out.

I imagine that his brother and sister match each other on roughly half of their auDNA (that's strong indication that they are full siblings); but he matches each  of them on only about 1/4 of auDNA (that's consistent with being a half-sibling -- or a nephew or a niece); and he has significant X chromosome matches with both brother and sister (that's consistent with having the same mother, since males have no X chromosome DNA from their fathers).
Yes, that was what I was wondering, but he wouldn't know that for sure until all their results were at GEDmatch.
I don't know what Ancestry tells people about their DNA matches and relationships.
Not much.
I had my dna tested, then my brother did his, his came back with us "close family to first cousin", he called they advised we shared a mother, then our sister got tested she comes up as immediate family to brother and close to first cousin to me.  Ancestry and GEDmatch show what appear to me matches on moms side, as well as others.  I am not sure where to go or what to ask
Yes, Ellen, what you say I think is right. Ancestry report says FOR ME amount of shared DNA:

brother: 1892 centimorgans shared across 63 DNA segments

sister:  1850 centimorgans shared across 58 DNA segments

For my brother to my sister he shares 2565 centimorgans across 55 dna segments.  That explains about all I know
All three of you should upload your data to Gedmatch so you can see your matches on a chromosome map.
I'm not sure how Ancestry would know you shared a mother.  I would expect they could definately tell you shared a parent by the size of the segments matching.  I don't think they have any mtDNA info as that would be one way to know if it was a mother you shared.  You might share an x chromosome with all of them which would be an indication as that can only come from your mother.  They may have that info behind the scenes, one more thing not shared with their customers.   GEDmatch is the only way to see how they all match up and what chromosomes you match on.   On average half siblings share 1753cM and full siblings 2600cM, so that is within the ranges.  Here are some links that might be of interest:



If he shares significant X chromosome material with his siblings, that confirms that they have the same mother, or at least are related on the maternal side. (I believe that essentially the same DNA match would appear if Raymond was a biological nephew or uncle of these siblings -- if he was the child of another "sister" or if he was actually his mother's biological brother.)

It seems unethical for Ancestry to have this information, but not disclose it fully to its customers.
Ancestry must have the info, because when we download our raw data from Ancestry and put it up on GEDmatch or FTDNA, the X chromosome info is there.
+6 votes
It is much easier for a male to discover his biological father by using a Y-DNA test.  I recommend starting with a Y-DNA37 test from Family Tree DNA.   

A Y-DNA37 test is likely to reveal your father's surname, because Y-DNA always follows the direct paternal line and surnames usually follow the direct paternal line.
by Peter Roberts G2G6 Pilot (543k points)
that I will do, thanks

I agree wholeheartedly with Peter. For males with completely unknown paternity, a y-DNA test should be your first action. As Peter suggested, 37 markers should be the least you test. You could start with 37 markers and then decide later about upgrading.However, considering its importance to you, I would probably go "all in" and opt for the 111-marker test right away. Most men can use DNA and their surname to screen matches. You will only have the y-DNA results to guide you. 

Related questions

+6 votes
1 answer
120 views asked Feb 7, 2018 in Genealogy Help by Sir William Arbuthnot of Kittybrewster G2G6 Pilot (170k points)
+8 votes
2 answers
+2 votes
1 answer
73 views asked Oct 31, 2019 in WikiTree Help by Lisa Alon-Hilleli G2G2 (2.1k points)
+6 votes
3 answers
+9 votes
3 answers
162 views asked Oct 15, 2017 in WikiTree Tech by Sandy Pittock G2G Crew (860 points)

WikiTree  ~  About  ~  Help Help  ~  Search Person Search  ~  Surname:

disclaimer - terms - copyright