Three founder mutations in BRCA1 are common in Poland (5382insC, C61G, and 4153delA). At birth, it is expected that 50% of the children of a parent who carries a BRCA1 mutation will inherit a mutant allele. However, in a recent paper we observed a greater than expected frequency of mutation carriers among daughters (but not among sons) of women with BRCA1 mutations in Poland. We observed 75 car...