What is the importance of Cookie, Regina's mother, in the memoir, Etched in Sand?

Cookie was a violent alcoholic who verbally and physically abused her children, though she often focused her cruelty on Regina. Cookie was a self-centered woman who spent money for her own vices such as alcohol and cigarettes, even when there was literally nothing for the children to eat. She often left them alone and the children were usually happier and healthier when they were fending for themselves, though this meant they were often reduced to theft or begging in order to feed themselves. Each time social workers or other officials became involved, Cookie pretended the children were lying, and the officials often believed her. That was seen when Regina contacted the Idaho child protective services in an effort to get Rose out of Cookie's custody, only to have Cookie say that Regina was a promiscuous alcoholic who had a history of lying. Cookie died while Regina was still relatively young, and Regina felt no sadness at losing this connection.