To continue the "gender in Hebrew" questions (like "meaning-of-grammatical-gender-in-hebrew-for-inanimate-objects)".
What can be more masculine than the fathers, and still, the Torah uses the feminine form in the plural (Ber 47):
"וַיֹּאמֶר פַּרְעֹה אֶל־אֶחָיו מַה־מַּעֲשֵׂיכֶם וַיֹּאמְרוּ אֶל־פַּרְעֹה
רֹעֵה צֹאן עֲבָדֶיךָ גַּם־אֲנַחְנוּ גַּם־אֲבוֹתֵינוּ"
Any sources, please?