The addition of a genotyped biological parent will allow your Ancestry Composition results to be phased and that phasing to be visible in Split View. Phasing refers to the process of separating the mixed genotype results for each location into the two haplotypes, one from each parent. You can then see the contribution from each of your parents to your overall Ancestry Composition:
Linking biological children in the Family Tree will also yield higher-resolution results in Ancestry Composition, but Split View requires the addition of a biological parent. It will only be calculated when one or both parents have been properly linked in the Family Tree.
Once you have a parent genotyped, you can add them to the Family Tree via the following steps:
Invite your parent to share genomes. They must accept the invitation for you to proceed. If you and your parent(s) share an account with multiple profiles, this step is not necessary.
Go to your Family Tree and add your parent to the tree by clicking either the "add father" or "add mother" nodes:
You can also use the "Add Relative" button in your profile's bio box:
Use the "Connection" tab to connect your parent’s 23andMe profile. Your owned profiles and shares will appear in the "select a profile" drop-down list:
Once a profile is successfully connected, chromosomes will appear on its node in the Family Tree.
You can also link to a parent from DNA Relatives by clicking on the predicted relationship and setting a confirmed relationship. Be sure to select "Connect this family member to my Family Tree" if you want to take advantage of this feature.