<Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (February 2017) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (February 2017) (Learn how and when to remove this template message) </Td> </Tr> <P> Maggie is first introduced in the penultimate episode of the tenth season . Cristina Yang interviews various different candidates to replace her as the head of her department in Cardiothoracic surgery . Maggie, having finished high school and medical school early, becomes head of her department at 31 years old . It is revealed in the season 10 finale "Fear (of the Unknown)" that Maggie's biological mother was Ellis Grey . Richard Webber is shocked by this, knowing he is her biological father . Throughout the eleventh season, Webber struggles to deal with the revelation and keeps it from Maggie . Maggie explains that 2 years prior, she looked for her birth mom and needed to go to the court for the records . She found out that she was dead, but got her name, and discovered that she was an amazing surgeon that worked at the Seattle Grace Hospital . She stated that that's not why she took the job, but it's "a little bit" why she took the interview . </P> <P> When Maggie identifies Meredith Grey, her half - sister, she attempts to bond with her . However, Meredith attempts to take charge and conflicts with her on a case . After several arguments, Maggie tells Meredith that she is her half - sister . Meredith, in disbelief, points out that she would know that her mother would be pregnant when she was five years old, as Maggie is five years younger than her . Meredith works with Alex Karev to decide whether Maggie is lying or if she is wrong . They discover she is correct . Meredith gets flashes back to the time of her mother's crisis at five years old, and remembers being at a hospital and hearing a screaming baby . After several weeks, Webber admits to Maggie that he is her father . Maggie is angry at him . Later, when he comes to apologize for not being there as a father, Maggie corrects him and says he is not her father, as she has adoptive parents she loves, and that she is only angry because of his dishonesty and making her look foolish and naive for weeks . Derek and Meredith decide to have Maggie come over to their house for dinner, to get to know Maggie better . After Maggie says yes, Derek decides it is a good idea to ask Richard as well . Richard reluctantly agrees . The night of the dinner, Maggie and Richard show up, but no - one answers . Maggie leaves him after that . Maggie develops a relationship with radiologist, Ethan Boyd . She admits her awkwardness in relationships, having ended her previous engagement to Dean, who she was unable to sleep in the same bed with . Meredith ends up in a bind with no one to watch her kids, so Maggie offers to watch them . Richard and Maggie eventually come to good terms, and Maggie's helping with Meredith's kids help her integrate into her family home more . Maggie learns about the histories of Meredith, Alex and Callie Torres as they commemorate their dead friend, George O'Malley . </P>

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