The family which produced Dolores Umbridge included her father Orford, a low-level Ministry of Magic employee, his Muggle wife Ellen Cracknell, and their two children, one of whom was a Squib. Ellen eventually left the family, taking her squib son with her, and returned to the Muggle world. Dolores did everything she could to distance herself from the family, saying instead that she was a pureblood and a member of the Selwyn family.
The sad tale of the Umbridge family mirrors that of Snape. Each was a mixed marriage between Muggle and magical people and each resulted in troubled children. Both families were unhappy and broken. Although the family of Minerva McGonagall stands in contrast in many ways, that family also had its share of sadness and disconnect because of the mixing of the two cultures. - SVA