*Men who produce high-quality sperm likely to have sons
“Dads can alter the sex of their offspring”, according to a Oxford University lecturer.Men who produce high-quality sperm are more likely to have sons, new research reveals.The findings were published in the journal Proceedings of the Royal Society B.
This comes after previous research suggests mothers have more influence over their offspring’s sex as experiencing the high physical costs of pregnancy makes them more likely to invest resources into determining their child’s gender.
Past research also reveals sperm quality is affected by chemicals found in soap, sunscreen and plastic.Lead author and lecturer, Dr. Aurelio Malo, said: “In a nutshell, we now know that dads, as well as mums, can alter the sex of their offspring”.
Researchers from Oxford University analysed a species of mice native to the United States (US).Results reveal fathers with higher-quality sperm produce ‘heads’ with smaller nuclei, which houses genetic material in cells.
Smaller nuclei results in men producing a higher proportion of sperm with a Y chromosome, which leads to the production of more sons than daughters.Previous research, from the Nofer Institute of Occupational Medicine in Lodz, reveals sperm quality is affected by hormone-disrupting chemicals, known as parabens, found in soap, sunscreen and plastic.
Parabens are significantly associated with an increased number of abnormally sized and shaped sperm, which has previously been linked to infertility. Malo said: “Mothers can influence their offspring in a number of ways from copulation to birth, whereas fathers have control over sperm only. This gives mothers more scope to alter the sex ratio of their offspring…”
“The physical costs of gestation are obviously higher for the mother, so it’s in her own interests from an evolutionary point of view to invest her resources wisely in terms of the sex, size and quality of her offspring.
“Predicting sex ratios has great interest for humans. In domestic species, such as livestock and pets, the ability to manipulate sex ratios has important economic implications.
“In endangered species, skewed population sex ratios can push species to the brink of extinction, so breeding programmes could pair males and females according to individual attributes that help achieve the rarer sex at birth.
“In a nutshell, we now know that dads, as well as mums, can alter the sex of their offspring, and that the ability to do so might have evolved through natural selection.”