Do you all start out being female?

Answer 1

This is the theory because all femle ova have female chromosomes.. Sperm have male and female chromosomes. If the sperm containing female chromosomes then nothing changes during fertilization. If male chromosomes, then changes take place to cause the cells to produce a male. There is scientific theory that this may be a cause of homosexuality in that the changes do not occur as expected. But this is only theory.

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They don't necessariy start as female, but they do have female organs. It is the presence of chemicals (due to Y chromosome) that forms the male organs from the female organs later on.