Thread:Juraj103/@comment-26222852-20150905143429/@comment-3131473-20150906101240

Gemma was descendant of Aideen, an illegitimate daughter of one of Kaedweni monarchs, so probably the Unicorn was added thanks to her marriage with Gedovius.

By the way, I think that the in-game tree is based on the previous version of tree, the one made by Ortelius Team. It contained some errors since it was based on wiki descriptions instead of Sapkowski's notes.