Question about identical SNP's in otherwise distant relatives

[dhchilies]

We have 5 individuals in our family group who are not closely related based on the usual markers. However, they have 15 identical SNP's listed.
Everything I have read says the SNP's are just random mutations and not useful for genealogy. However, my scientist brain tells me that the likelihood of getting 15 identical random mutations is vanishingly small without a common ancestor.
I would like someone to help me understand this. The only possibilities I can see as reasonable are:
1. Common ancestor
2. Error in the lab
3. Really crazy and improbable chance like winning the lottery.

What am I missing here?

[Wing_Genealogis]

1. Common ancestor is correct answer

I liken SNPs to Hansel & Gretel's bread crumbs, as it leaves a trail of cues following the path into the past.

I would strongly encourage folks to join their haplogroup project to learn more about the SNPs in your branch (whether it be I1, U152, or U106). Next Generation Sequencing (such as the Big Y and other tests) will revolutionize SNP testing.

[Jessant]

We have 5 individuals in our family group who are not closely related based on the usual markers. However, they have 15 identical SNP's listed.

Do the identical SNPs appear in this list?

Itaï Perez, Re: [DNA] It’s been a month, let’s start complaining about Geno 2.0 transfer errors. GENEALOGY-DNA-L Mailing List, http://archiver.rootsweb.ancestry.co...-01/1358179571, 14 January 2013

It's also possible the SNPs in question are positioned near the base of the Y tree (and therefore common to most branches). Try running your data through ytree.MorleyDNA.com

[Jim Barrett]

We have 5 individuals in our family group who are not closely related based on the usual markers. However, they have 15 identical SNP's listed.
Everything I have read says the SNP's are just random mutations and not useful for genealogy. However, my scientist brain tells me that the likelihood of getting 15 identical random mutations is vanishingly small without a common ancestor.

What am I missing here?

I think the main thing you are missing is providing us with information.

Which "usual markers" and which "15 identical SNP's"?

If they have Y-DNA results, what level have they tested to and what are the genetic distances?