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Ten years ago the scientists had come to know that sperm with X chronsome runs faster than ones with Y chromsome when they run in electropherosis together. You can check this article in New England Medical Journal of 1992, if I don't make a mistake. Furthermore, sperms with X chronsome can live longer than ones with Y chronsome. That is the reason why we get so many girls when we do pregeant experiment outside mothers body. However, intending to having a boy or a girl makes sense. The keypoint is the acidic enviroment in vagina and uterus. So some try to scratch some acid directly to the wall of vagina. Basically I don't like to use artifical methods to destroy the nature balance. If parents have some genetical diseases which males and females have different results, some methods can be applied. Otherwise, just let it be. |
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