It's all about Dad's genes Let's return to the ultrasound discussion. When I tell patients there's about a 50/50 chance for either sex, I also tell them the father's genes determine the baby's sex since some of his sperm carries X chromosomes and some carries Y chromosomes.
What we can say is that dad's sperm determines whether a baby will be born as a boy or a girl. About half of his sperm will make a boy and half a girl. The sex of the baby depends on which sperm gets to the egg first.
The mother gives an X chromosome to the child. The father may contribute an X or a Y. The chromosome from the father determines if the baby is born as male or female. The remaining chromosomes are called autosomal chromosomes.
All men inherit a Y chromosome from their father, which means all traits that are only found on the Y chromosome come from dad, not mom. The Supporting Evidence: Y-linked traits follow a clear paternal lineage.
There are many ideas about ways to influence baby's sex and how to conceive a boy or a girl, but these are mostly myths or "old wives' tales" that aren't supported by modern science. The only reliable way to choose a baby's sex is by using IVF with genetic testing.
Timing of intercourse
The timing of when a couple has sex is thought to actually make a difference in helping to conceive with a boy. It is one of the strategies suggested in The Shettles Method, which claims that the chances of having a boy are boosted when conception occurs as close to ovulation as possible.
The key to conceiving a boy is to do “the deed” close to your ovulation. As Dr Shettles points out, male-producing sperm (Y-chromosome) move faster than female sperm. Male sperm also dies pretty fast, while female-producing sperm (X-chromosome) can stick it out and take their time hooking up with the egg.
They found that the most fertile months for conceiving a boy were from September to November, while the lowest fertile period was from March to May.
Nature is designed to favour the conception of boys from September to November and girls from March to May because of an evolutionary mechanism aimed at keeping the overall sex ratio as near to 50:50 as possible, the scientists said.
Since the 17th century, scientists have noticed a slightly tilted sex ratio at birth: 51 percent of babies born are boys.
It's all about Dad's genes
A man's X and a woman's X combine to become a girl, and a man's Y combines with a woman's X to become a boy. But if the sperm don't have equal Xs and Ys, or if other genetic factors are at play, it can affect the sex ratio.
Conclusion. The Chinese birth calendar claims 93-99% accuracy in predicting infant gender based on month of conception and maternal age at delivery. In this large delivery dataset, accurate prediction of fetal gender based on the Chinese birth calendar was no better than a coin toss.
Overall, 51.2% of the first births were male. However, families with boys were significantly more likely than expected to have another boy (biologic heterogeneity). By the fourth birth to families with three prior boys, 52.4% were male. The increase varied directly with the number of prior boys (p for trend = 0.0007).
Check out SneakPeek Gender Test to find out your baby's gender as early as 6 weeks at 99.9% accuracy! It's generally understood that the chances of having a boy or a girl boil down to 50/50 odds—essentially a coin toss. Heads for boys, tails for girls! If you really want to test those odds, check out our Gender Quiz!
There are lots of theories and claims made about influencing the chances of having either a boy or a girl baby, but the scientific facts are absolutely clear. The chances of having conceiving a boy or a girl are almost exactly equal for each and every pregnancy.
Genetically, you actually carry more of your mother's genes than your father's. That's because of little organelles that live within your cells, the mitochondria, which you only receive from your mother.
We inherit a set of 23 chromosomes from our mothers and another set of 23 from our fathers. One of those pairs are the chromosomes that determine the biological sex of a child – girls have an XX pair and boys have an XY pair, with very rare exceptions in certain disorders.
Each parent will pass one copy of their eye color gene to their child. In this case, the mom will always pass B and the dad will always pass b. This means all of their kids will be Bb and have brown eyes. Each child will show the mom's dominant trait.
In genealogy, the male lineage is often traced using the Y chromosome because it is only passed down from the father. All individuals carrying a Y chromosome are related through a single XY ancestor who (likely) lived around 300,000 years ago.
Genetically, you actually carry more of your mother's genes than your father's. That's because of little organelles that live within your cells, the mitochondria, which you only receive from your mother.
And while it is true that you get half of your genes from each parent, the genes from your father are more dominant, especially when it comes to your health.