Tasuki comes from a fairly large family consisting of mainly females. Its his family that drove him to run away from home when he was fourteen and become a member of the Mt. Leikaku bandits. Without his family, we wouldn't have the Tasuki that we all know and love!
Tasuki's parents remain without names but they made their appearance in the manga when Tasuki and the others visited his house. His mother appears to be the figure-head of the family and is very out spoken though kind. His father, on the other hand, seems to be very intimdated by his wife and we get the impression that he just goes along with whatever she says. Note that Tasuki's hatred for milk came from his mother who, according to Tasuki, suffocated him with her "enormous breasts" while breast feeding him as a baby.
There are five other children in Tasuki's family, all female and all older than he is. They constantly picked on him and made his life miserable. Living with six strong-willed women is sure enough to drive anyone nuts and it's no wonder why Tasuki ran away from home. It's also no wonder why his father appears to be so meek. Tasuki's sisters remain unnamed, with the exception of the youngest daughter, Aidou.
Aidou is a very kind and well-brought up young woman. She's polite to everyone but Tasuki, who she likes to pick on. While we don't know much about Tasuki's family in general, it's hard to tell if Aidou is either the worst or the kindest to Tasuki. We do know that she is a strong woman who helps out around the house as much as she can and strongly disapproves of Tasuki's running away. Aidou is the only daughter who remains unmarried, a subject that Tasuki will make fun of her for. Of course, any comment Tasuki makes ("Old maid!") results in Aidou hurling a log at his head.
There used to be a rumor floating around that Tasuki's other four sisters were named Jiang, Li'an, Pa'liu and Mai, however this rumor is false... These four names were given to the other sisters in a fanfiction and are not official names. We have yet to find out what Tasuki's sisters are called.