You can simply go in on the ethnicity page and edit parent 1 & parent 2 to read Mother & Father (if you know which is which) and then your matches will identify Mother's side or Father's side.
Pheno
That is what I did just now, so my matches now appear as Mother, Father or unassigned whereas before they only had mother or father if I had put that manually.
There are two things that puzzle me about this in particular -
One is that, if they are putting Parent 1 and Parent 2 (or whatever) against matches, even brand new ones without trees, how come some of the matches are unassigned?
The second is that, where there are shared matches, there are several occasions where all but one of the matches show one parent's side and the remaining one shows the other parent's side. I now have a pretty extensive tree and can find no incidence of someone from my father's family having a child with (or even being acquainted with) someone from my mother's family. I realise it is quite possible that this has happened since I am not omniscient but is there any other explanation anyone knows of?
EDIT: I've just realised that this has been extensively discussed on another thread so I do apologise for repeating it.
