Premium Parental Inheritance shows you which side of your family each ancestry region in your results came from. It's powered by Family Phasing, a method that uses your existing DNA relatives to determine parental origin — no connected parent required.
The feature is available to 23andMe+ ® Premium subscribers.
Getting Started | How Family Phasing Works | Understanding Your Results | Inheritance Calculations | FAQs
Getting Started
Premium Parental Inheritance is available to 23andMe+ ® Premium subscribers in the US, Canada, and UK.
Once you subscribe to Premium, your results will begin computing automatically, no action needed.
If you're currently on an Ancestry Service or Health + Ancestry Service plan, you'll see an upgrade path from your Ancestry Composition and Ancestry Overview pages.
How Family Phasing Works
Your chromosomes come in pairs: one chromosome in each pair comes from your mother, the other from your father. Determining which genetic information came from which parent is called phasing.
Previously, Parental Inheritance required a connected biological parent. By directly comparing your DNA to a parent's, we could determine which portions of your ancestry came from which side. Without that connection, there was no way to assign DNA to a parent so the feature simply wasn't available to you.
Family Phasing solves this by analyzing patterns of DNA sharing across many of your DNA relatives in the 23andMe database. By looking at which segments you share with relatives whose family side is known and aggregating that signal across enough matches, the method can statistically determine which portions of your genome came from each parent, even without a direct parent comparison.
The more relatives you have in the database, and the more closely related they are, the more confidently we can determine which side each portion of your DNA came from. Your results include a general view that assigns every ancestry region to a parental side, plus a toggle between two stricter confidence levels if there are regions assigned with lower confidence.
Understanding Your Results
You'll see your Ancestry Composition results split into Parent 1 and Parent 2, showing how much of each ancestry region you inherited from each side.
If you don't know which label corresponds to which parent, that's expected. You can use your ancestry percentages as clues. For example, if Parent 1 shows a high percentage of Irish ancestry and you know that runs on your dad's side, you can rename Parent 1 to "Paternal Side."
If one of your parents has tested with 23andMe and is participating in DNA Relatives, you'll see them connected to their corresponding side automatically.
If you want a more conservative view, there is a confidence table below with two stricter thresholds you can toggle between if there are regions assigned with lower confidence. At these levels, some regions that were assigned to a side in the general view may instead show as inconclusive.
Inheritance Calculations
It's not uncommon for Parental Inheritance to show slightly more or less than 50% from each parent. This is because Ancestry Composition uses both the autosomes (chromosomes 1–22) and the X chromosome to calculate inheritance, and the X chromosome isn't passed down equally to both sexes:
- Autosomes (chromosomes 1–22): Passed down equally from each parent, one copy from each. A parent and child share 50% of their autosomal DNA.
- X chromosome: Women inherit two X chromosomes (one from each parent). Men inherit one X from their mother and one Y from their father — so men's X chromosomes are assigned entirely to the mother's side.
As a result, Parental Inheritance for men may show greater than 50% inherited from the mother and less than 50% from the father. This is expected and correct.
Note: The Y chromosome and mitochondrial DNA are not used when calculating inheritance percentages.
FAQs
Do I need a parent to have tested with 23andMe?
No. Premium Parental Inheritance uses Family Phasing, which works from your existing DNA relatives in the 23andMe database. A connected parent is no longer required.
What subscription do I need?
Premium Parental Inheritance requires a 23andMe+ ® Premium subscription. If you're on an Ancestry Service or Health + Ancestry Service plan, you'll see an upgrade path from your Ancestry Composition page.
What if I don't have many DNA relatives?
Results depend on the number and relatedness of your DNA relatives in our database. The more relatives you have, and the more closely related they are, the more confidently we can determine which side each portion of your DNA came from. Your results include a general view that assigns every ancestry region to a parental side, plus a toggle between two stricter confidence levels if there are regions assigned with lower confidence, where uncertain regions may show as inconclusive instead.
How long does it take to get my results?
Results begin computing automatically when you subscribe to Premium. If you tested before this feature launched, there may be a short delay before your results are ready. You'll receive a notification when they're available.
Why does my Parental Inheritance show less than 50% from one parent?
This is expected for men. Because men inherit their X chromosome only from their mother, the mother's side includes the length of an extra chromosome that the father's side does not, resulting in slightly more than 50% from the mother and less than 50% from the father for male customers.
Can connecting a parent still improve my results?
Yes, it may, especially if you don't have many close relatives in the database. A connected parent covers essentially your entire genome, while DNA relatives only cover the portions you share with them. Phasing with a parent is typically both more complete and more accurate than phasing with more distant family members alone. Connecting a parent also makes your results easier to read, since that parent appears directly in your report, making it clear which side is which instead of having to infer it from your ancestry percentages.