In Vayishlach (Bereishis 33:6-7), Yaakov's wives and children bow to Esav. With regard to the maidservants and their sons, the verse states וַתִּשְׁתַּחֲוֶיןָ - in the feminine, whereas by Leah and her sons, as well as by Yosef and Rachel, it says וַיִּשְׁתַּחֲווּ - in the masculine. Why?
The Rosh and Chizkuni (in his second explanation) and Daas Z'kenim answer that the maidservants' sons didn't bow, as they thought that they, as freemen, were more important than their mothers. That's why it says "bowed" in the feminine: only women bowed. [Presumably "and their children" in the verse refers to approaching.]
Chizkuni's first explanation is that the maidservants' sons didn't bow because they thought Esav wouldn't care about their bowing since they were mere sons of maidservants.