A product of experimental gene splicing; Tokkea's mother was abducted by Cerberus while pregnant and was subject to intrusive procedures that led to the daughter being infused with Asari DNA. After being freed by a Salarian strike team, Tokkea was refused entry to the Turian military as her unique visual features made many officials view her as an abomination.
She wound up serving in the Salarian military instead as they welcomed her in, largely because a lot of them were fascinated with how successful the results of Cerberus were. However other Salarians that knew her personally tried to shield her from those individuals.
Also worth noting that because she was never actually a part of Turian culture, she never got any markings on her face from her own kind. But the small Salarian family she found herself with marked her with an ancient symbol from their people; the symbol for "Miracle".