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Although each egg cell produced by a woman carries a single X chromosome, the sperm cells produced by a man carry either an X or a Y. This means, in very simple terms, that the sperm cell determines a baby's sex.
Although each egg cell produced by a woman carries a single X chromosome, the sperm cells produced by a man carry either an X or a Y. This means, in very simple terms, that the sperm cell determines a baby's sex.