Why Siblings Don't Share the Same Amount of DNA With Matches?

[@jonathanflores9874]

I have a perfect example. My sister same parents always favored our grandmother. She took a DNA test along with my sister and myself and confirmed my sister matched our grandmother over 37% instead of my usual 25% that I inherited. She looks just like grandma so it makes perfect sense. It all depends on who you favor.

[@FamilyHistoryFanatics]

I have a related video about inheriting DNA from grandparents. Have you seen this one? kzbin.info/www/bejne/mZOkhH6ff9pjq8k

[@dianneeastwood6397]

Hi Andy, My bio father was adopted in 1933, and I wasn't raised by him. I had my DNA done and discovered 3 unknown half-siblings all have different bio mothers. I have used the Wato tool to the best of my ability and think it's probable I found our bio grandparents. How do I know if my half-siblings are actually half vs double 1st cousins? My thoughts are this would impact the bio grandparents from the WATO tool.

[@FamilyHistoryFanatics]

Look at each one with a chromosome browser. Half siblings shouldn't have any fully matched regions. Double 1st cousins will have some small segments (still above 10cM) that are fully matched.

[@dianneeastwood6397]

Thank You 😊

[@karinathomas9706]

Thank you Andy. I have seen this difference between my sister, 2 brothers and my matches; I will try the distribution on an unknown match. All I have been able to learn is that the match belongs to our paternal maternal maternal line; we don't know who our great-grandmother's father was. Maybe this would help get a little closer to that answer.

[@FamilyHistoryFanatics]

I think this video needs a follow up with some unknown examples to show how using multiple siblings (and known cousins can help)

[@glenjones6980]

What I lack in quality matches I more than make up for in quantity. I've spent a week or two looking at the low matches that were assigned to a parent and was surprised how many matched to some of the bigger matches. As often as not they seem to have the better researched and sourced trees too which is a big bonus. In a week or two I'm hoping the test I sent to a close family member will be completed and the results added to my account, it will be interesting to see how the two set of results stack up and with luck show where my dna takes a swerve in a certain direction.

[@chriskeller272]

Good video. I was wondering if there is a cM sex difference among siblings? I noticed that your cousin is son of your Aunt. Does the recombination difference between your dad and your aunt mean there is a cM difference between these two as well?

[@FamilyHistoryFanatics]

My initial response is no. But I am going to have to look into that because of the recombination difference between maternal and paternal DNA,

[@invadertifxiii]

do u have videos explaining the communities on ancestry and how accurate they are

[@FamilyHistoryFanatics]

I do have such a video. Check this one out. kzbin.info/www/bejne/gqXFe2iqlLusbqc

[@invadertifxiii]

@@FamilyHistoryFanatics thank u I was scrolling and looking

[@suzannemcclendon]

Thank you for this video, Andy. My maternal half-sister and I have a full 2C1R from our maternal grandpa's side. On Ancestry, I match her at 61cM and my sister matches her at 12cM. In our 1st cousin group of me, my half-sister, another 1C and her paternal half-sister, and two other non-sibling 1Cs, we have some wide variances, too. We are all full 1Cs to each other. The 1C who I match the highest matches one of the other 1Cs lower than she matches my children, who would be her 1C1Rs. I understand about the variances, but that one really surprised me. What I don't understand is how to read a histogram. Could you please do a video about how to do that? I have one in my camera, too, and have no clue how to make sense of it or the one on DNA Painter. Thank you!

[@FamilyHistoryFanatics]

A histogram video is a great idea. I'll put it in the hopper.

[@suzannemcclendon]

@@FamilyHistoryFanatics Thanks!

[@sie4431]

I swear you did a similar video years ago but I haven't been able to find it. The main lesson I think is to not write off more distant matches. You might only have 20cm with that person but a sibling or parent could have 70cm making them more relevant

[@FamilyHistoryFanatics]

Reason to test as many siblings and cousins as you can.

[@angelawheeler3944]

Hi, Hoping you can help! I have a grandmother, who I believe to be illegitimate. I know scant details about her mother and no information about her father. Recently I noticed a DNA match with myself, a 2nd to 3rd cousin, 137 cm and 2% DNA. I was excited thinking that we probably shared a Great Grandfather or Great Great Grandfather. (Possibly my grandmother’s father) I started to research the 2nd-3rd cousins family to find she has two siblings. One sibling, 4th-6th cousin, 48 cm and 1% DNA and the second 42 cm and 1% DNA. My question is , what is most probably the ancestor we share?. Am I likely to find who is my gradmother’s father is? Thanking you in advance. Angela 0:51

[@DonovanFamilyHistory]

Regarding the new Maternal / Paternal match splitting feature that is in Beta. I manage several kits and all of them got the new feature around Nov 6th, but now on Nov 11th, several of them have lost the new feature. Do you have any thoughts why one of 2 siblings might loose the feature? If they are re-evaluating kits for endogamy, i would think that would apply to both siblings.

[@FamilyHistoryFanatics]

We don't work for Ancestry and our negativity about their ethnicity tools hasn't strengthened our relationship with them. (But, we're going to be honest about our opinions since we see all the confusion these tools generate). So, we don't have any insights to share. Sorry.

[@frankiedollar5407]

Is it possible for my brother and I to have the same parents but different ethnicity ❓

[@FamilyHistoryFanatics]

Yep.

[@paulorasantos]

Thank you for this video and for all the others, which are very informative. I have a doubt, maybe you can tell me something about. My two sisters and I have a match with someone and each one of us share a different amount of DNA, as you explained in the video. One of my sisters share only 11 centiMorgans with this person, however her son, my nephew, shares 116 centiMorgans with the said person. How is it possible? If the mother shares only 11 cM, how can her son share 116 cM? Do you think this can be an error? Thanks for the attention.

[@FamilyHistoryFanatics]

I would look at how that person is related on the other side of each of your families. (You each have two parents so one or both could be related through both parents rather than just one). I did a video recently on unequal sharing between parents and children with the same match.

[@jasonborn867]

I'm not sure this question is necessarily relevant, but hoping Andy or someone else can shed some light. It's my understanding 3% shared DNA represents on average a 3rd cousin, and that decreasing percentages on average represent more distant ancestors. Eventually testing can no longer detect a shared percentage of DNA because too many generations have passed, which precludes validating a genetic connection even though physical records may document related ancestry. Taking these factors into account, how is it that 3% of my DNA is Neandertal when the genetic transfer occurred some 40,000 years ago? I raise this question because it would seem such a distant relative's DNA would be undetectable after some 2,000 generations yet 3% Neandertal DNA is a standard finding for most non-African populations. Thanks for any feedback on this question, and please accept my apology if unrelated to genealogy.

[@chriskeller272]

Most of your DNA isn't autosomal so the 3% means two different things.

[@jasonborn867]

@@chriskeller272 I thought 44 out of the 46 chromosomes are autosomes with the remaining 2 being sex chromosomes... Wouldn't that make most of our DNA autosomal? I'm still confused on the 3% question above and thought Andy would jump all over it... lol. No one seems to know but there must be an answer to the question... thoughts?

[@chriskeller272]

@@jasonborn867 You are right about the chromosomes. People misleadingly refer to DNA as all one thing. Initially when you spoke of 3% you're talking about the coded region only, which is only about 10% of your DNA. When they speak of 3% Neanderthal DNA they are talking about something else.

[@jasonborn867]

@@chriskeller272 Hello again, Chris, and thank you for the follow up. It sounds like fully understanding how 3% is calculated for both examples may require a detailed and perhaps tedious explanation--which is a bit much to ask on a youtube platform. Is there any online references you could advise that fully explain how the two calculations are derived? If you read this, Andy, feel free to share any resources as well. Thanks Chris!

[@chriskeller272]

@@jasonborn867 Sorry Jason I don't know much about DNA other than Andy 's videos, but given that there probably is Neanderthal DNA in the coding region, just well below the 7cM threshold of the initial 3% calculation, determing what is Neanderthal DNA is extremely complex and not well understood.

[@jeanninecathcart627]

I'm a girl, I found out that my closest match is a boy first cousin. Does gender matter?

[@FamilyHistoryFanatics]

With autosomal DNA, not really.

[@James-w6x9v]

Ok one sister one brother same father.one sister being french indigenous.the brother being Asian indigenous Americans.does this mean the father had his son with a different mother.

[@milonguerobill]

Still does not answer the question "Why ?".

[@faithhowe6170]

I can explain the answer to "Why" this way: each child gets half of their DNA from each parent, think of it as each parent holds a deck of cards that the child chooses from, about 3400 centimorgans worth or so. The next child then picks their 3400+centimorgans from the same parents decks, and so on.The chances of 2 siblings picking the exact same cards are very minuscule. It's from these chosen centimorgans chosen that you match with cousins, One sibling may have picked 110 centemorgans that match, while another may only have picked 35. This is also why some siblings may share an ethnicity that other siblings don't have. I hope this helps you.

[@suzannemcclendon]

I can tell you what I was told that I hope will answer the "why". Pretend your parents are passing out M&Ms or Skittles. Your parents just reach in the bowl and grab a handful of those M&Ms for each of the kids. One kid might get more brown, another more yellow, another more green, and another more blue. It is a random grab of colors each time. Each color represents a grandparent's DNA. Let's say the match in question is on your mom's side. Let's assign your maternal grandparents the colors green and blue. Just as an example, your own Chromosome 2 has segments green, blue, green. Your sister got all blue on this chromosome. Your brother got blue where you got the first green and blue and the rest of his Chromosome 2 is green. Your maternal cousin, however, got blue where you got green and got green for the rest of that chromosome. In the above example, you and your brother would match that cousin on the third segment because you three are green there. Your brother and sister would also match the cousin on the first segment because the three of them have blue there, where you have green. You, your brother, and sister all match on the second segments because the three of you are blue there, but none of you match the cousin there because he/she has green there. I hope that made sense. It is all random, just like an M&M toss. :)

[@FamilyHistoryFanatics]

Thanks Faith and Suzanne for responding to Bill. Y'all did well.

[@suzannemcclendon]

@@FamilyHistoryFanatics You're welcome, and thank you, too!

[@S612yendi]

She is such a liar! She’s done nothing! She needs to stay in California with all the other weirdo’s