Private User
There has been a bad merge here, it is not that Gerhard has the wrong parents it is that he has the wrong birth and death dates.
Reading Medlands (i have no other source) the profile that you are talking about "Gerhard III" is listed as "Gerhard I", the son of Heinrich is listed as "Gerhard II".
I don't know who Gerhard III is or if there even is one listed on Medlands.
It looks like at some point the profiles of Heinrich's uncle and Heinrich's son have been merged, possibly creating a Data Conflict, resulting in a profile occupying the location in the tree of the uncle but containing the data of the son.
If i am reading correctly Gerhard I was graf von Egisheim _only_, he must have had no sons because his nephew Heinrich (who is heir to his father's title of graf von Dagsburg) is known as graf von Egisheim und Dagsburg. Heinrich with two sons seems to have split the lands between them so that Gerhard II is also only graf von Egisheim. So regardless of which Gerhard the profile is supposed to be the Title/Surname(?) is wrong.
As for his wife marrying his son, well there is no son mentioned in Medlands (as i'm sure you know) so it suggests more bad merging.
Looking at the Revision Tab there was a merge in 2011 between Gerhard III and Gerhard IV (Geni profiles not Medlands naming), the wife probably got duplicated in this process.
It is altogether possible there never was a son.
Justin Durand any suggestions of other sources that we could compare Medlands with?