Announcement

Collapse
No announcement yet.

Determining half vs full siblingship

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Determining half vs full siblingship

    My niece (daughter of my older sister) and I wish to test to determine if her mother and I share the same mother or have different mothers. No other family member is available for this testing.
    Three basic questions:
    1. Which test kits do I order for us?
    2. What information will it yield?
    3. Will it come with interpretation of results, or will I have to hire someone to interpret the results?

    Thank you for whatever guidance you can offer me.

  • #2
    Well for your case, the only options that would help would be Family Finder and/or mtDNA Full Sequence. Family Finder tests for both of you should be more than enough.

    The mtDNA FS test could help mostly if your maternal line (mother's mother's mother's etc) was really different from your niece's maternal line. If the results were so different you would know your sister's mother was not your mother. However, if they are different yet somewhat related like if your sister's mother descended from an aunt of your mother, then the test could make you think you had the same maternal line with possibly minor or no difference.

    So your best bet is the Family Finder. It looks at DNA you get from all sides of your family. It gives you a list of cousin matches, which are people that match you on a segment of your DNA. So you and your niece should match each other.

    Then all you need to do is compare how much DNA you have in common with your niece. To do this transfer the data to Gedmatch.com (which is free) so you can use their tools to compare both kits and see how much DNA you have in common. If your sister had the same parents as you, your niece and you shall have more DNA in common. If your sister only had one parent in common, then you will have less DNA in common.

    The DNA in common will be in ceniMorgans (cM). Take a look at the chart here:
    http://isogg.org/wiki/Autosomal_DNA_statistics

    Look for "aunt-or-uncle/niece-or-nephew" and then "half-uncle or aunt/half-nephew or niece". Remember these are estimates. Your values will differ. These values can also be altered if say your niece's father was somehow related to you.

    Do remember the kits they send come with their own kit number. One is meant for you and the other for your niece. Don't mix them up. If you wish to save money on the test, you can wait for a sale or discount. They come during holidays and special events. Though for a FF test you probably would only save $10 or so. As for interpretation, you can always ask questions in these forums and people will give their opinions.

    Comment


    • #3
      She wasn't clear if her sister is available/willing to be tested. If so it would be better if both sisters test (Family Finder).

      Comment


      • #4
        Family Finder is all you need. I do not see a cost-benefit in doing the mtDNA additionally under these circumstances.

        Comment


        • #5
          Definitely FamilyFinder. FamilyFinder will give you total cM shared, longest Block Shared, and a Relationship Range.

          They used to also show "Suggested Relationship" on the Main Page - now to see that - look on Chromosome Browser - suggest, click on Find by Name, enter name for Niece - then click on that in the suggested list to see her Profile.
          Other way to see Suggested Relationship now - download and look there - they did not revise it out of there when they re-did the Main Match Screen.
          If Suggested Relationship is Aunt/Niece then you and her mother are probably full sisters.

          If not, you can post figures here and ask again for how others would interpret the results and/or are they definitive.

          Comment


          • #6
            Originally posted by The_Contemplator View Post
            Well for your case, the only options that would help would be Family Finder and/or mtDNA Full Sequence. Family Finder tests for both of you should be more than enough.

            The mtDNA FS test could help mostly if your maternal line (mother's mother's mother's etc) was really different from your niece's maternal line. If the results were so different you would know your sister's mother was not your mother. However, if they are different yet somewhat related like if your sister's mother descended from an aunt of your mother, then the test could make you think you had the same maternal line with possibly minor or no difference.

            So your best bet is the Family Finder. It looks at DNA you get from all sides of your family. It gives you a list of cousin matches, which are people that match you on a segment of your DNA. So you and your niece should match each other.

            Then all you need to do is compare how much DNA you have in common with your niece. To do this transfer the data to Gedmatch.com (which is free) so you can use their tools to compare both kits and see how much DNA you have in common. If your sister had the same parents as you, your niece and you shall have more DNA in common. If your sister only had one parent in common, then you will have less DNA in common.

            The DNA in common will be in ceniMorgans (cM). Take a look at the chart here:
            http://isogg.org/wiki/Autosomal_DNA_statistics

            Look for "aunt-or-uncle/niece-or-nephew" and then "half-uncle or aunt/half-nephew or niece". Remember these are estimates. Your values will differ. These values can also be altered if say your niece's father was somehow related to you.

            Do remember the kits they send come with their own kit number. One is meant for you and the other for your niece. Don't mix them up. If you wish to save money on the test, you can wait for a sale or discount. They come during holidays and special events. Though for a FF test you probably would only save $10 or so. As for interpretation, you can always ask questions in these forums and people will give their opinions.

            Comment


            • #7
              Thank you for offering me such valuable and useful information.
              I am now able to proceed.

              Comment


              • #8
                Originally posted by mattn View Post
                She wasn't clear if her sister is available/willing to be tested. If so it would be better if both sisters test (Family Finder).
                My sister is not willing to b tested.

                Comment


                • #9
                  Based on what you said in your first post, I figured it meant your sister wasn't around to take the test. If it helps, you could try to explain the process of the test to her.

                  When I was trying to get an uncle tested, he was hesitant. It was never clear to me why. Once I told him of others who agreed to test and that he did not need to go anywhere or do anything, he was more than willing to take the test. I suppose he may have thought it might be painful (like a blood sample) or that he would have to go somewhere to take the test (like a clinic). Whatever reason your sister could have, may simply be a misunderstanding of what she thinks the test will do. Or maybe she fears learning the answer to the question you are trying to answer.

                  At any rate, whoever does take the test, make sure you scrape well. Don't do it if you recently ate, drank, smoked, brushed your teeth, etc. Give it like half an hour or more after any of that or similar activities to make sure it doesn't affect the sample you collect. Scrape for at least half a minute to maybe near a minute per cheek. The better the sample, the less time you will wait for the results.

                  Comment


                  • #10
                    I agree that the Family Finder test would be your best option to start with.

                    It should give you the answer based on the amount of DNA shared.

                    A niece/nephew of a full sibling should share roughly 1400 to 1700 cM in DNA.

                    A niece/nephew of a half sibling would be approx. 850cM.

                    http://isogg.org/wiki/Autosomal_DNA_statistics

                    Edit.
                    Best results would be if you could convince your sister to test, as full siblings would show full identical segments (sharing both maternal and paternal) when comparing via Gedmatch or David Pike Utilities.
                    Last edited by prairielad; 12 March 2016, 10:59 PM.

                    Comment


                    • #11
                      Originally posted by The_Contemplator View Post
                      Based on what you said in your first post, I figured it meant your sister wasn't around to take the test. If it helps, you could try to explain the process of the test to her.

                      When I was trying to get an uncle tested, he was hesitant. It was never clear to me why. Once I told him of others who agreed to test and that he did not need to go anywhere or do anything, he was more than willing to take the test. I suppose he may have thought it might be painful (like a blood sample) or that he would have to go somewhere to take the test (like a clinic). Whatever reason your sister could have, may simply be a misunderstanding of what she thinks the test will do. Or maybe she fears learning the answer to the question you are trying to answer.

                      At any rate, whoever does take the test, make sure you scrape well. Don't do it if you recently ate, drank, smoked, brushed your teeth, etc. Give it like half an hour or more after any of that or similar activities to make sure it doesn't affect the sample you collect. Scrape for at least half a minute to maybe near a minute per cheek. The better the sample, the less time you will wait for the results.

                      Comment


                      • #12
                        Clarification

                        Do I order two kits?
                        Do The give you the option upon ordering to send one to yourself and another to a family member in another state?
                        How will they know to compare our DNA? Will the ordering of two separate kits allow a place to explain what information I am seeking?
                        I realize that these are basic questions, yet since I haven't done this before, I do appreciate the basics bring spelled out.
                        I would ask these questions to a customer representative, yet I've been repeatedly been placed on hold for long wait times without success.

                        Thank you very much.

                        Comment


                        • #13
                          Originally posted by dianemarie58 View Post
                          Do I order two kits?
                          If two different people are being tested, yes, you have to order two kits, each separately. Every customer of FTDNA has their own kit number, which is the unique identifier of their DNA sample. If two people ordered using the same kit number, there would be confusion about whose DNA was being tested.

                          Originally posted by dianemarie58 View Post
                          Do The give you the option upon ordering to send one to yourself and another to a family member in another state?
                          Since you're going to order two different kits, you can put different names and addresses in the online order. However, if you want to be the person overseeing the results and matches of your relative, then put your e-mail address as the contact address for both kit orders. FTDNA will send an e-mail with the kit number and password to whatever address is used in the order. If your relative has no objection and you want to have access to your relative's account, then use your e-mail address for both your order and your relative's order.


                          Originally posted by dianemarie58 View Post
                          How will they know to compare our DNA? Will the ordering of two separate kits allow a place to explain what information I am seeking?
                          FTDNA will compare your relative's and your DNA results to the entire Family Finder database and find anyone who shares enough DNA to be declared a match. This is not the same as a paternity testing company, which only compares your DNA to a specific person who also submits their DNA for the specific purpose of proving a relationship. In fact, Family Finder costs less than a paternity testing service and is much more powerful and definitive in declaring a relationship, since a paternity testing service only tests a few dozen locations on the chromosomes while Family Finder tests 700,000 locations.

                          You don't need to explain what you're hoping to find from the test. Since FTDNA is comparing your results to the entire Family Finder database, they will report to you all your matches. If your relative is a match to you, she'll appear in your match list and as one of your closest matches.

                          Comment


                          • #14
                            Thank you for supplying succinct and comprehensive responses which are easy to understand.

                            Comment

                            Working...
                            X