In the article, Concepts – Parental Phasing, I explained why it’s so important to have at least one, if not both of your parents DNA tested in addition to your own DNA. Having at least one parent tested allows you to determine, at least for the matches that match both of you, which side the genetic ancestral connection is from, assuming the match is only from one side.
At GedMatch, you can utilize the kit of you and one parent to subtract out the DNA of your known parent. The results are the other half of your DNA, that of your missing parent. Now, this technology isn’t perfect. Let’s say for example that you have your mother, as I do, but not your father. At one location, you and your mother both have an A and a T. There is no way to know whether you inherited the A or the T from your mother, and which one you inherited from your father, so these situations are unresolvable.
So are areas where they are no-calls or bad reads.
In other studies that I’ve been involved with, we can obtain a significant amount of your half of the other parents’ DNA, around 40% of their entire DNA sequence. So that’s certainly better than nothing, given that you only have 50% of their DNA to begin with.
A New Series – Managing Autosomal DNA Matches
I’m going to step through how to create a second phased parent at GedMatch, because you’re going to need to do this for one of the upcoming Concepts Series – Managing Autosomal DNA Matches articles. Yes indeed, I’m introducing a new series soon – and this article is to help you prepare!
Test Your Parents and Close Family Members Now!
So here’s a big hint for the new series. If you have a parent who has not yet tested, now is the time to order that test. You can test at Family Tree DNA or at Ancestry and then transfer your results to Family Tree DNA and GedMatch. However, if you order from Ancestry, make sure to read this article first to understand fully the rights you are conveying to Ancestry. Also, Ancestry is changing to a new chip, and we’re not sure how compatible their new autosomal file will be with either Family Tree DNA or GedMatch, and we won’t know until after those vendors have had some time to evaluate the new chip file results, so perhaps Family Tree DNA would be the safer bet right now for new tests, because you will need to transfer your parents results to both Family Tree DNA and GedMatch. Yes, you will need your known relatives results in both locations, because relatives help identify match and triangulation groups.
So, order that kit today so you’ll have results and can fully participate in the new series’ exercises. We’ll we walking through matching, phasing and triangulation vendor by vendor one step at a time to create your own matching DNA Master file.
No Parents to Test? You’re NOT Out of Luck!
If you don’t have either parent, you’re not entirely out of luck. You won’t be able to participant in parental phasing, BUT, you will be able to participate in other types of phasing and matching. In order to do this, you’ll need to test as many of your relatives as possible, beginning with testing as many half or full siblings as possible.
Test any grandparents, aunts, uncles, great-aunts, great-uncles and any and all cousins that you can find and arm-twist (in the nicest way of course) too, because their matches will help you – and that goes for whether you have one, both or neither parent tested.
The only people in your family you don’t need to test are people both of whose parents have tested, or the relevant parent (to you) has tested.
For example, if your first cousin has tested, you don’t need her child too, because that child inherited half of your first cousin’s DNA, and you already have that in your first cousin’s test. However, your first cousin’s sibling is an entirely different matter, and you’ll want to test as many cousins (and their siblings) as you can find.
Creating a Parent at GedMatch
To create a phased parent, you’ll need your kit and the kit of one of your parents. If you have both parents tested, you don’t need to do this.
Sign into your GedMatch account and select the Phasing option, 6th from the top.
Enter the kit number of the child, which is you, and the kit number of the parent whose DNA you do have.
Click on generate.
When the utility is finished, you will receive the following message.
GedMatch has created a phased maternal and paternal kit with the leading letters PM (for 23andMe kits), PT (for Family Tree DNA kits) and PA (for Ancestry kits) and the trailing letters P1 and M1. P1=Paternal and M1=Maternal.
The kit number of the child is imbedded inbetween PM and P1, so for example in PT524738P1.
These phased kits, because they are only “half kits,” can be utilized to determine which of your matches are from which side of your family.
I wrote about how to do that in the article titled, Phasing Yourself.
But let’s be very clear here, a phased kit is never as good as the real McCoy, so by all means, get that parent tested if at all possible.
Have fun and get your ducks in a row for the new series!
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