But that's not exactly true – there's actually a slight bias toward male births. The ratio of male to female births, called the sex ratio, is about 105 to 100, according to the World Health Organization (WHO). This means about 51% of deliveries result in a baby boy.
Almost everyone has around a 50% chance of having a boy and a 50% chance of having a girl. 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.
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.
Men carrying a gene that leads to their sperm having more Y chromosomes have more sons. During times of war and large casualties of male soldiers, those families are more likely to have more surviving sons. And when those men have children, they, like their fathers, might be more likely to have baby boys.
Best positions: deep penetrative sex is preferable. This helps to deposit the semen and sperm closest to the woman's cervix so they are given the best opportunity to get to the egg in the fallopian tube. Twelve hours before ovulation is thought to maximise the chances of conceiving with a boy.
The work by Corry Gellatly, a research scientist at the university, has shown that men inherit a tendency to have more sons or more daughters from their parents. This means that a man with many brothers is more likely to have sons, while a man with many sisters is more likely to have daughters.
Fertility treatment
Some fertility drugs work by stimulating a woman's ovaries, which can sometimes cause them to release more than one egg. If sperm fertilizes both of these eggs, this can result in twins. In vitro fertilization (IVF) can also increase the chance of conceiving twins.
Well, it turns out male offspring - so boys - inherit more genes from their mothers. The way this works is that when it comes to the sex chromosomes, females get two X chromosomes, one from their mother, one from their father, whereas males get an X from Mom and a Y from Dad.
Men determine the sex of a baby depending on whether their sperm is carrying an X or Y chromosome. An X chromosome combines with the mother's X chromosome to make a baby girl (XX) and a Y chromosome will combine with the mother's to make a boy (XY).
Over a period of time, science explained that male sperms determine the baby's sex, depending on whether it is carrying X or Y chromosome. Since a woman carries two X chromosomes, if a man's sperm is carrying X, a baby girl will be born and if his sperm is carrying the Y chromosome, it will be a boy.
Which parent genetically determines the gender (sex) of a baby? Neither parent is fully responsible for determining the sex of the baby. However, all eggs produced by the female have an X sex chromosome, and all sperm from the male have either an X or Y chromosome.
But more than half of all human conceptions die during gestation, and this results in a sex imbalance at birth. “Overall, more females die during pregnancy than do males. So that's why there's an excess number of males at birth,” said Orzack, who has published research on this issue.
If you already have a boy, the chance that the next baby is also a boy is 50 percent. It's all a matter of mathematics. A couple having 4 children of the same gender in a row happens actually more often than you might think. In fact, one in eight couples (12.5%) with 4 children have 4 of the same sex.
About 40% of parents, across the decades, have told researchers that if they could only have one child, they would want a boy. Only a consistent 20% to 30% has chosen a girl or no preference. At least when it comes to what we think we want, the data is clear.
A study published in the Proceeding of the Royal Society B found that women with diets high in potassium (found in bananas, as well as potatoes, clams, and artichokes, among other foods) are more likely to bear sons.
Men determine the sex of a baby depending on whether their sperm is carrying an X or Y chromosome. An X chromosome combines with the mother's X chromosome to make a baby girl (XX) and a Y chromosome will combine with the mother's to make a boy (XY).
Because boys have the sex chromosomes XY, they must inherit their Y chromosome from their father. This means they inherit all the genes on this chromosome, including things like sperm production and other exclusively male traits.
In the XY sex-determination system, the female-provided ovum contributes an X chromosome and the male-provided sperm contributes either an X chromosome or a Y chromosome, resulting in female (XX) or male (XY) offspring, respectively. Therefore it is said that father determines the sex of the child.