Might this be The Shamer's Daughter by Lene Kaaberbøl, the first book in the The Shamer Chronicles series...?
There are four books in the series, with the first having been published in 2000 and the last in 2003.
Here's the Goodreads synopsis for the first book:
Dina has unwillingly inherited her mother's gift: the ability to elicit shamed confessions simply by looking into someone's eyes. To Dina, however, these powers are not a gift but a curse. Surrounded by fear and hostility, she longs for simple friendship.
But when her mother is called to Dunark Castle to uncover the truth about a bloody triple murder, Dina must come to terms with her power--or let her mother fall prey to the vicious and revolting dragons of Dunark.
Someone asked a story-ID question about this series on Goodreads, and according to their description, the story is set in medieval times, and the protagonist, Dina, has an older brother and a younger sister, neither of whom have her powers.
Hi guys wondering if you can help me! I was talking to someone about books that I read when I was younger and I could not remember what they are called! Hopefully someone can help here! It was a series set in medieval times - the main character was a teenage girl who had powers and so did her mother - her older brother and younger sister did not. The mother was taken away to a big city. The girl eventually followed. The leader of the place they lived and the guy who ordered the girls mom to be taken away wasere - was called something like Dracon or Draco - something to do with Dragons. She also eventually met her father who also had powers as well but a different type. The girls mother and father had her in order to create an even more powerful being. I think there were about 4 books in the series and I remember reading it in 2007! If anyone can help I would greatly appreciate it!!!
The Goodreads synopsis for the second book in the series, The Shamer's Signet, mentions a brother named Davin.
One look into the Shamer's eyes and a person's darkest secrets are revealed
Dina has recently come into her uncomfortable powers as a Shamer, and now even her brother, Davin, no longer dares to meet her gaze.
Yet in these dangerous times there are far worse things in store for the young Shamer, who is kidnapped and forced to use her gift as a weapon against innocent people. Dina must get free. Can her brother help her escape?