The Jadwiga are the direct descendants of the Witch Queen Baba Yaga, who travels to Golarion once a century to install a new daughter to the throne of Irrisen. Even though Baba Yaga hails from somewhere else in the Great Beyond, the Jadwiga appear, and seem to be fully human.
They are the ruling class of Irrisen, with the descendants of Elvanna, the current queen of the land, holding the highest political and social positions. This will change in 4713 AR when Baba Yaga returns to remove Elvanna and the first generation of her children from Irrisen and replaces them with a new daughter and progeny.
The term Jadwiga comes from Queen Jadwiga, the first ruler of Irrisen, but is often mistranslated as “children of the witch-mother”.