Anne de Bretgane cannot be the mother of Dorothea. Anne of Brittany was 12 years old when married(remotely)and this marriage to Maximilian lasted only 2 years in contract form and was cancelled. Dorothea may have been the illegitimate daughter of Anna von Helfenstein with Maximilian. They had 9 children, so it was a long relationship.
https://en.wikipedia.org/wiki/Maximilian_I,_Holy_Roman_Emperor
here is another source which lays doubt as to the cetainty of Dorothea's mother's identity
http://fmg.ac/Projects/MedLands/OLDENBURG.htm#GeorgChristiandied1665A (scroll down to chapter 4)
"JOHANN “der ältere” (-6 Jun 1572). Graf zu Ostfriesland 1538. m (Brussels 11 Nov 1539) DOROTHEA von Oesterreich, illegitimate daughter of Emperor MAXIMILIAN I & his mistress ---. Heiress of Falkenburg, Durbuy and Dalem. Emmius records the marriage arranged in Brussels “ante Eidus Novemb.” 1539 between “comiti Ennoni...fratre Ioanne” and “Dorotheæ” whose dowry was “Durbuyum oppidum...in finibus Lucelburgi principatus...Falcoburgii et Dalæ præfectura in ulteriore ripa Mosæ”[238]. Beninga records the marriage in 1539 of “Graven Johan tho Oostfreeslant” and “Dorothea van Ostenryck, Keyser Maximilians natuerliche dochter”[239]. No reliable indication has been found about the identity of Dorothea’s mother."
Hester van Heemstra
Hi Hester Johanna van Heemstra
I couldn't quite see the connection between your link and Dorothea, this one is direct http://fmg.ac/Projects/MedLands/AUSTRIA.htm#Dorotheadied1572
I have disconnected the mother from Dorothea, on Geni, and locked her profile so no new mother can be connected without a Curator's involvement. I also merged her duplicate husband into the MP version.
Thank you for fixing this. My link was from a list of noble families, you had to scroll down to chapter 4, then to Edzard, then to Johan, where it quotes a document on the marriage of Johan and Dorothea, which declared her to be a "natural daughter" of emperor Maximilian- i.e. illegitimate, but nothing about who the mother was. But all this is not needed to disprove, when only looking at birth and death dates(wikipedia): Dorothea was born in 1516 and Anne of Brittany died in 1514. This leads me to question how attributions are made on Geni- this doesn't look like the genealogical "gold standard" was applied in this case. Another question I ask is WHY are there SO few primary and historic documents posted under sources or media? Whoever at Geni is responsible for the standards should be requiring attributions by "volunteer" curators to demonstrate proof, at the very least some degree of double checking- like birth & death dates, and basic history. The general public can be forgiven, but not curators.