Can the amount of saliva affect how many centiMorgans are shared between 1st cousins?


I share 279 centimorgans with a 1st cousin in 12 segments. I don't believe that is enough to be considered 1st cousins. She says she couldn't spit a lot.

Would a small amount of spit affect the outcome of the relationship?

Mary Ann

Posted 2019-01-15T02:40:02.987

Reputation: 51



Absolutely not.

The amount of saliva is a factor in whether or not you get DNA results at all. If you have them, that's it. While there is such a thing as "partial results" it's because you need multiple passes of the DNA sequence to make sure there aren't errors. No testing company will give you results if they don't get enough passes. A very small amount of saliva (like if they're taking it from a 50 year old sealed envelope) might have this problem. If you don't have enough saliva for a proper test at a basic genetic genealogy company, they ask you to repeat the test.

In your case, I'm afraid the answer aren't first cousins.

The expected range for first cousins is 553-1225 cM.

One strong possibility is that you are half first cousins, as the range for that is 137-856. There are many other possible relationships with 279 cM, but the others are less likely to be passed off as full first cousin.

Cyn says make Monica whole

Posted 2019-01-15T02:40:02.987

Reputation: 2 426

1... or could be 1st cousins once removed. – lkessler – 2019-01-15T19:54:33.197

1@lkessler Yes, it can. I didn't list everything because there are many possible relationships based just on the cM number. The most likely relationship that fits into a family secret is half first cousin (one parent isn't really the parent). The second most likely is, as you say, first cousins once removed (if the not-first-cousin has a "sibling" 14+ years older, or a similar is not uncommon for a teen to have or father a baby then the grandmother claims to be the mom and raises the child). – Cyn says make Monica whole – 2019-01-15T19:58:34.883