The question "Who will we have — a boy or a girl?" has concerned prospective parents since ancient times. This curiosity has spawned countless folk omens, theories, and "tested" methods of planning a child's sex. Blood rejuvenation, Chinese calendars, special diets, and even certain positions for conception — you can find it all on the internet. But what of this has any scientific basis, and what is merely a myth? Let's find out.
How a child's sex is determined: school biology
First of all, it's worth recalling the basics. The sex of the future child is determined at the moment of fertilization and depends solely on which sperm reaches the egg first.
- Female egg always carries only one type of sex chromosome — X.
- Male sperm come in two types: some carry an X chromosome, and others — an Y chromosome.
Thus:
- If the egg (X) is fertilized by a sperm with an X chromosome, the resulting set is **XX** — a **girl** will be born.
- If the egg (X) is fertilized by a sperm with a Y chromosome, the resulting set is **XY** — a **boy** will be born.
Thus, **the child's sex is 100% determined by the man**. The probability of having a boy or a girl is roughly equal — 50/50.
Popular myths about sex selection
The scientific community does not confirm the effectiveness of any of the following "folk" methods.
Myth 1: Shettles Method (timing of intercourse)
Theory: This method is based on the assumption that "male" Y-sperm are faster but less durable, while "female" X-sperm are slower but live longer. Accordingly, to conceive a boy, intercourse should be as close as possible to ovulation, and for a girl — 2-3 days before it.
Reality: Modern studies have not been able to confirm a significant difference in speed and endurance between X- and Y-sperm. The effectiveness of this method does not exceed statistical error.
Myth 2: Special diets
Theory: Consuming certain foods supposedly changes the acidity of the environment in a woman's body, making it more favorable for "boy" or "girl" sperm. For example, for a boy they recommend eating more meat and bananas (potassium, sodium), and for a girl — dairy products (calcium, magnesium).
Reality: There is no evidence that diet can influence the pH of the reproductive tract enough to give an advantage to one type of sperm. Moreover, strict restrictive diets can harm health. A balanced nutrition for both partners is much more important.
Myth 3: Chinese and Japanese calendars, blood rejuvenation
Theory: These methods are based on the mother's age, month of conception, or cycles of "blood rejuvenation" in the parents.
Reality: This is pure numerology and superstition, having no relation to biology or genetics.
Myth 4: Conception positions
Theory: Deeper penetration supposedly helps the "fast" Y-sperm reach the goal more quickly.
Reality: As we already know, positions do not affect the chances of conception in principle, let alone the child's sex.
Can you choose a child's sex at all?
The only reliable method of sex selection is **pre‑implantation genetic diagnosis (PGD)**, which is performed as part of the in‑vitro fertilization (IVF) procedure. Embryologists check the chromosomal makeup of embryos before they are transferred to the uterus.
However, in Ukraine and most countries worldwide, sex selection using PGD is permitted only for medical indications — for example, to prevent the transmission of sex‑linked hereditary diseases such as hemophilia.
Conclusion
Today there is no proven and safe "home" method to plan a child's sex. The best strategy for prospective parents is to focus not on attempts to "program" the sex, but on creating the best conditions for the birth of a healthy baby. Whether it's a boy or a girl — let it remain a pleasant surprise!
