I thought breast cancer also followed paternal lineage. my paternal grandmother and aunt, both died in 50's and my cousin is fighting a second occurrence (my age - 50's). i got myself checked, but breast center only asked about mom's side.

Breast Center correc: Statistically, it is only the maternal side of the family, and probably only first-degree relatives (mothers, sisters, aunties) whose history of breast cancer affects a woman's genetic risk.

From both sides: Perhaps they keep asking you about your mother's history because you already have told them so much information about your father's family.

Both lines can pass : The breast cancer genes which have been identified so far are called "autosomal" meaning that they can be passed on through either the maternal or paternal lineages.

True: Most inherited breast cancers are associated to mutations in the genes brca 1 and 2. These mutations can indeed come from your father's side. People with suspicious family history like yours should visit a professional with expertise in inherited cancers. Good for you for being aware of this.

Maternal or paternal: Either of your parents can transfer cancer genes (i.e. Brca1/2), including breast cancer genes.