"son" is intended to include both masculine and feminine is borne out by the context, and, in fact, the whole history of the race. Being itself must be masculine and feminine, in order to make man in its image and likeness, "male and female."
Analyzing these divine ideas, or sons of God, we find that they manifest characteristics that we readily identify as masculine or feminine. For example, life is a son of God, while love is a daughter of God. Intelligence is a son of God, and imagination is a daughter of God. The evidence that sex exists in the vegetable and animal worlds is so clear that it is never questioned, but we have not so clearly discerned that ideas are also male and female. The union of the masculine and feminine forces in man is most potent in the affectional nature, and that these forces should endure and never be separated by external causes was laid down as a law by Jesus. He said, as recorded in Mark 10:6-9
From the beginning of the creation, Male and female made he them. For this cause shall a man leave his father and mother, and shall cleave to his wife; and the two shallbecome one flesh; so that they are no more two, but one flesh. What therefore God hath joined together, let no man put asunder.
We should clearly understand that each of the various ideas, or sons and daughters of God, has identity and in creation is striving with divine might to bring forth its inherent attributes. It is to these ideas, or sons and daughters, that Being, or Elohim, says: "Let us make man in our image, after our likeness" (Gen. 1:26)