Maybe I have some terminology wrong, or I misunderstand something about pedigrees, but isn't the proband the starting point of a study? Why is he not included in the cohort? If you look at the link:
We have proband's parents, and then some offspring (proband's?), but where is the code for the proband him/herself? Who is he/she in this family tree and cohort?
So far I assumed NA12878 is the proband due to the ubiquitousness of that sample.