I’m reading a novel where Person A and Person B have a 98% probability of being siblings. Or rather, 98.4% of their DNA is a match (according to the wording in this novel).
Now in the real world, as opposed to made-up-novel-world, is that accurate? Watching too many “Is x your father?” Tv shows has taught me it’s either a 99% probability or pretty close to zero.
Divine Angel said:
I’m reading a novel where Person A and Person B have a 98% probability of being siblings. Or rather, 98.4% of their DNA is a match (according to the wording in this novel).Now in the real world, as opposed to made-up-novel-world, is that accurate? Watching too many “Is x your father?” Tv shows has taught me it’s either a 99% probability or pretty close to zero.
My parents were siblings and there match was 99%, they found out later as they were separated when young, explains the extra nipples I have I expect
You sure do get bored at work, dontcha? 😊
Divine Angel said:
You sure do get bored at work, dontcha? 😊
I have no idea what you mean
Searching reveals the below table
Relationship Average % DNA Shared Range
Identical Twin 100% N/A
Parent / Child
Full Sibling 50% Varies by specific relationship
Grandparent / Grandchild
Aunt / Uncle
Niece / Nephew
Half Sibling 25% Varies by specific relationship
1st Cousin 12.5% 7.31% – 13.8%
1st Cousin once removed 6.25% 3.3% – 8.51%
2nd Cousin 3.13% 2.85% – 5.04%
2nd Cousin once removed 1.5% 0.57% – 2.54%
3rd Cousin 0.78% 0.3% – 2.0%
4th Cousin 0.20% 0.07% – 0.5%
5th Cousin 0.05% Variable
6th Cousin 0.01% Variable
DNA sharing is interesting
You can get people who look very similar but aren’t related at all, is this just facial features or is body shape, etc also the same
I wonder if you tested their DNA would you get a higher than average DNA match or can the DNA that makes up their facial features for example be completely different with very little or no matches at all but look the same
Divine Angel said:
I’m reading a novel where Person A and Person B have a 98% probability of being siblings. Or rather, 98.4% of their DNA is a match (according to the wording in this novel).Now in the real world, as opposed to made-up-novel-world, is that accurate? Watching too many “Is x your father?” Tv shows has taught me it’s either a 99% probability or pretty close to zero.
When was the book written? In the olden days they didn’t have modern DNA fingerprinting.
But we are talking about two different things. You’re talking about probability of paternity (which yeah will be 0% or >99.9%) whereas the author is talking about a % match. which isn’t a realistic idea. You don’t share 98.4% of your DNA with your father. If they mean a direct copy comparison, then two randomly selected people have around 99.9% similarity, whereas if they mean consanguinity, then there is 50% consanguinity between a person and the person’s father.
The novel was published this year. The plot revolves around a missing child, who is thought to have ended up overseas and the person searching for her has had their DNA tested. As siblings, he says there’s a 98.4% match between their DNA, thus “proving” they are related.
In this made up novel world, there’s obviously going to be a twist. I’m just wondering if 98.4% matching DNA is a real thing.
in forensics we don’t use the word ‘match’ it’s a likelihood based on the evidence…
we can only tell (by DNA) if a person is female or male, nothing else.
When they are trying to establish familial links, or criminal links, of known samples with collected samples they use markers (up to 21, maybe 24, I believe now) which establishes a probability beyond reasonable doubt.
Arts said:
in forensics we don’t use the word ‘match’ it’s a likelihood based on the evidence…we can only tell (by DNA) if a person is female or male, nothing else.
When they are trying to establish familial links, or criminal links, of known samples with collected samples they use markers (up to 21, maybe 24, I believe now) which establishes a probability beyond reasonable doubt.
Ooo, look at you being all sciency. We may have to revoke you handle.
Arts said:
in forensics we don’t use the word ‘match’ it’s a likelihood based on the evidence…we can only tell (by DNA) if a person is female or male, nothing else.
When they are trying to establish familial links, or criminal links, of known samples with collected samples they use markers (up to 21, maybe 24, I believe now) which establishes a probability beyond reasonable doubt.
First you tell us they can only determine sex, then you tell us they use markers for reasonable doubt tests…
TIL what centimorgans are. Dunno how I missed that before.
poikilotherm said:
Arts said:
in forensics we don’t use the word ‘match’ it’s a likelihood based on the evidence…we can only tell (by DNA) if a person is female or male, nothing else.
When they are trying to establish familial links, or criminal links, of known samples with collected samples they use markers (up to 21, maybe 24, I believe now) which establishes a probability beyond reasonable doubt.
First you tell us they can only determine sex, then you tell us they use markers for reasonable doubt tests…
well, they can see the markers but they don’t know what they mean (as in skin colour, eye shape etc)… but a marker of the same size, width and position as the known sample (repeated for the number of points they look for) is a reasonable determination of a high likelihood
yeah, so centimorgans are used to measure the distance between the markers .. great similarity between the known sample and collected sample would indicate a similar source (along with the other descriptors above)
I watched a youtube last night. It might have been dodgy. They were doing those scrape your mouth genealogy tests. The siblings were 45-50% alike. The male was said to be mostly European. The sister had European and Asian and a touch of African.The brothers were more alike genetically.
sarahs mum said:
I watched a youtube last night. It might have been dodgy. They were doing those scrape your mouth genealogy tests. The siblings were 45-50% alike. The male was said to be mostly European. The sister had European and Asian and a touch of African.The brothers were more alike genetically.
yeah, I don’t know how they do that.. it could well be that certain markers and other heritage questions can align to a ‘reasonable assumption’.. or it could be that the forensic DNA lecturer didn’t have up t date information (though it was backed up by the practicing dna expert we had who visited us from chemcentre…)
sarahs mum said:
I watched a youtube last night. It might have been dodgy. They were doing those scrape your mouth genealogy tests. The siblings were 45-50% alike. The male was said to be mostly European. The sister had European and Asian and a touch of African.The brothers were more alike genetically.
https://news.nationalgeographic.com/2018/03/dna-ancestry-test-siblings-different-results-genetics-science/
Divine Angel said:
sarahs mum said:
I watched a youtube last night. It might have been dodgy. They were doing those scrape your mouth genealogy tests. The siblings were 45-50% alike. The male was said to be mostly European. The sister had European and Asian and a touch of African.The brothers were more alike genetically.https://news.nationalgeographic.com/2018/03/dna-ancestry-test-siblings-different-results-genetics-science/
Even twins can get noticeably different results from genetic ancestry tests, due to a biological process called genetic recombination.
—I was going to say that your 97%ers back there sound like identical twins.
sarahs mum said:
Divine Angel said:
sarahs mum said:
I watched a youtube last night. It might have been dodgy. They were doing those scrape your mouth genealogy tests. The siblings were 45-50% alike. The male was said to be mostly European. The sister had European and Asian and a touch of African.The brothers were more alike genetically.https://news.nationalgeographic.com/2018/03/dna-ancestry-test-siblings-different-results-genetics-science/
Even twins can get noticeably different results from genetic ancestry tests, due to a biological process called genetic recombination.
—I was going to say that your 97%ers back there sound like identical twins.
Make female siblings. Not even fraternal twins.
Ok, so “ a 98% match” is BS. I’ll be sure to note that in my review.
Divine Angel said:
sarahs mum said:
I watched a youtube last night. It might have been dodgy. They were doing those scrape your mouth genealogy tests. The siblings were 45-50% alike. The male was said to be mostly European. The sister had European and Asian and a touch of African.The brothers were more alike genetically.https://news.nationalgeographic.com/2018/03/dna-ancestry-test-siblings-different-results-genetics-science/
My sister did one last year. They came back and stated that they’d found a cousin in Scotland. Happened to be true :)
Divine Angel said:
HOLD ON, HOLD ON!
In the OP you stated, and I quote “Or rather, 98.4% of their DNA is a match”, and yet here lies proof positive that the novel does not state that at all.
See, I can pay attention.
Yeah, I must be more tired than I thought.
Divine Angel said:
Ah, that’s what I thought.
I have a 50% DNA match with my sister.
And a 96% DNA match to a chimpanzee.
So am I more closely related to a chimpanzee than to my sister?
No. It all depends on the test used to determine the match.
according to my DNA profile i’m 15 percent victim and celebrate my rich background with my people.
someone i know did a DNA test to celebrate the promised diversity from all the guff told to her by her family
disappointing 100 english / irish – no diversity and celebration for you
The standard sibling and paternity test used to use STR, short tandem repeats. But that was ten years ago. Tests may have got better since then, or worse if they’ve been made faster using for example lab on a chip analysis.
One website says that typical probabilities are 99.7% chance if you really are siblings as against 1.2% chance if you’re random individuals.
DNA Tests such as ancestry.com and 23andme can’t always distinguish between 2nd and 3rd cousins, or between 3rd and 5th cousins.
