‘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.
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’.
‘Dads can alter the sex of their offspring’, according to a Oxford University lecturer
DOWN’S SYNDROME TEST ‘USED TO CHOOSE GENDER’: WARNING OF ‘ARMS RACE’ TO CREATE PERFECT BABY
Genetic testing during pregnancy is driving an ‘arms race’ in the search for the perfect designer baby, experts warned in March.
A breakthrough in technology has meant babies with even minor genetic flaws can be identified early in pregnancy.
Tests are already available on the NHS to accurately identify unborn children with Down’s syndrome and other major genetic conditions.
Yet private firms are also using the tests to reveal the baby’s gender as early as nine weeks into a pregnancy.
Experts are worried this could lead to a surge of abortions on the basis of the unborn child’s sex.
A report by the Nuffield Council on Bioethics warned about the use of ‘selective terminations’ and says that in future any child with a problem as mild as an allergy may be seen as undesirable.
High-quality sperm produces sons
Researchers from Oxford University analysed a species of mice native to the 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.
‘Dads can alter the sex of their offspring’
Dr 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.’
The findings were published in the journal Proceedings of the Royal Society B.