I have sometimes been asked this question: ‘The Bible says that after Eve was created from Adam’s rib she was “bone of my bone, and flesh of my flesh” (quoting Adam). And Adam said, “She shall be called woman, because she was taken out of man.” Doesn’t medical science say all embryos when conceived are female, and it depends on the number of X and Y chromosomes in the embryo which decides the sex of the child before birth? How are these two reconciled?’
First of all we must realize that medical science does not say ‘all embryos when conceived are female …’ (although I once heard that remark on a TV game show!). As a teacher of genetics and medical physiology, I can assure you that medical science and genetics know that the sex of the child is determined at conception. Women always produce egg cells containing an X chromosome. Men produce two kinds of sperm cells, those containing an X chromosome and those containing a Y. These are produced in roughly equal numbers. If an X sperm cell fertilizes the egg, the child from the point of conception on is a girl (the XX chromosome condition). If it’s a Y-containing sperm cell that fertilizes the egg, the child is a boy from conception onward (the XY chromosome condition).
Note, incidentally, that in one sense it’s the father who determines the sex of the child, genetically and statistically speaking—although we know that it is God who plans our life, our gender and all, from before the foundations of the earth.
During embryonic development both sets of sex organs begin to develop in the young child, and the embryo passes through a so-called ‘indifferent’ stage. That does not mean the embryo is female. Neither is it distinctively male in anatomy yet, although whether it will become male or female was already determined from the time of conception. Depending on whether the initial chromosome condition was XX or XY, one system will develop further from the indifferent stage and the other relatively regresses. It is correct to say that the embryo is either male or female from the point of conception onward. It is never correct to say that the embryo was only female.
Although the embryo is normally either male or female genetically from conception onward, it is possible to change the sex later by hormone treatment and surgery, as is done in sex-change operations. Since God made of one flesh both the first man and the first woman, it is not surprising that the potential to go either way is present, even though the genetic sex is normally clear. Incidentally, maleness and femaleness often reside together in the tissues of animals and plants as well, reflecting the fact that God created them to multiply after their kind so that males and females will have chromosomes that are compatible and can be passed on during the reproductive process.