From the earliest times, people want to have an influence on the sex of their children. Many queens would save their position and even head then. Matter of continuity and succession of the dynasty of property are no longer so important today. However, now says that the real man must build a house, set a tree and generate a son. Women will hear that the only daughter of life-long "sticks to the house." The process of sex determination, we know more and more, to some extent we can have an impact. However, they are still uncertain sample, and the ethical aspect raises many questions.

Hippocrates wrote: "The man who wishes to have a daughter, he must approach the period after the wife and treat her lovingly each day, until the loss of its vital forces. The man who wants to have a son, he should approach his wife when she is want to. " The fact that women orgasm increases the chance of conception boy, remembers the Talmud. This is the modern discoveries. Not all the old theories and methods are equally accurate. The ancient Teutons, wanting to procreate a son, taken to bed with each other ax. In the Middle Ages, recourse to an alchemy. Back in the early twentieth century believed that if the spouse after the wife read of lives of famous men, she was born to a son. In 1917 English physician Dawson announced that the ovum from the left ovary after fertilization gives a girl from the right - the boy.

All heritable characteristics, from which we come to the world, stored in the genes are arranged on chromosomes. Each cell in the human body (except germ cells) is the kernel in its 23 pairs of chromosomes. 22 of them direct the construction and system operations. Last couple to sex chromosomes. In women they are the same (this means they are XX), a man different (X and Y). This double set of chromosomes is reduced in the process of maturation of reproductive cells in ovaries and testes. As a result, each and every contains only half the chromosomes (one from each pair), in which one sex. The eggs are always X chromosome, the sperm and the X or Y (half-half). If the sperm for fertilization of the X chromosome, the child was born, when the ovum penetration of the Y chromosome, a boy on the world to come.

Released from the ovary ovum goes along where there is fertilization. Of the millions of sperm released only one goal to reach (the rest are killed, or dies on the way after about 72 hours). Start of the race with time and struggle to survive. Sperm "male" - the Y chromosome - they are smaller and faster, but less live. Sperm "female" are slower, but more resistant to harmful environmental factors (acid reaction in the vagina, cervix barrier, etc.) and can survive longer. Ovum lives more or less daily. If the ratio is for a day or two before ovulation is more likely that, in the sperm survive the roads "female". If intercourse occurs during ovulation or just after a better chance in the race for the egg to the sperm for men.

The method consists in the observance of the dietary specific diet - rich in calcium and magnesium favors conceiving a girl, in the sodium and potassium - the boy. So, if you want to get daughter already for a few weeks before you should eat lots of dairy products, farinaceous foods, carrots, legumes, chocolate and honey, and avoid salt. But if you want to have a son, you should eat salty foods, a lot of meat, fresh and dried fruit, and denying the nuts, chocolate, natural bread and dairy products. All, however, within the limits of common sense. Too one-sided diet could badly affect the development of the child and lead to serious illness in the mother - (hypertension with diet "Boy" renal diet with "girl").

Laboratory methods is to extract the sperm by centrifugation and further selection. Uses are the differences in weight and size of spermatozoa with chromosome X and Y. The next step is the artificial insemination of the sperm of a particular type, often using micro manipulation. This method is very expensive, complicated and cumbersome for the spouses. Apply it only to the most specialized centers and it is only when the sex conceived child may make about its health (such inherited disease associated with sex is, for example, haemophilia, which affects only men).

The method of cyclic (called Selnas) is based on the recent discovery that the X and Y sperm differ in electrical potential: X sperm are positively charged, while the Y-sperm negatively. The potential of electric egg is changed periodically, so some days it attracts the sperm X, and Y Repel the other vice versa. For the determination of individual fertility calendar data is needed, inter alia, the date of birth a woman, her blood group, date of first menstruation and the menstrual cycle. To ensure that the author of this method, the French biologist Patrick Shoun, its efficiency is 98.7%. Some experience in this field has been limited, although some doctors already use this method.