For years, many families have believed that a child’s intelligence is inherited from the mother, a claim often repeated in casual conversations, parenting forums and social media.
But doctors and geneticists say intelligence cannot be traced to one parent, one gene or a single moment in pregnancy.
In a previous interview earlier this year, Dr Robbin Noreh, an embryologist at Nairobi IVF Centre, addressed questions around assisted reproduction and genetic traits, clarifying the limits of modern fertility technology.
While the discussion focused on sperm sorting and gene editing, Dr Noreh explained that these procedures are primarily used for medical reasons, such as preventing inherited diseases or supporting family balancing, not for selecting social traits.
“Post-sperm sorting, we are basically separating X and Y sperm chromosomes so we know this is a male or this is a female,” he said. “But gene editing involves modifying the genome or the embryo to achieve a particular desired trait.”
Gene editing often uses technologies such as CRISPR—a scientific tool that allows researchers to make precise changes to DNA by cutting, removing or modifying specific genes. Often described as “molecular scissors,” CRISPR holds promise in preventing serious genetic conditions, but its use in selecting social characteristics like intelligence, eye colour or talent remains scientifically unproven and ethically contentious.
“For example, someone has sickle cell; you edit the embryo so that the child cannot inherit that condition,” Dr Noreh said. He stressed that fertility clinics do not use gene editing for non-medical purposes. “We are not doing social; we are doing medical. The focus is on family balancing or medical conditions, not choosing traits like intelligence.”
No single gene determines intelligence, it is influenced by very many genes, from both parents.
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He also underlined the ethical frameworks guiding fertility treatments. “Someone can come and just say they want a baby boy, but we have to consider the long-term ethical implications,” he said. “Our approach is careful and moral.”
On the question of inheriting specific traits, including intelligence, Dr Noreh emphasised that fertility medicine does not determine or guarantee a child’s cognitive ability. “We are not doing social; we are doing medical,” he reiterated.
Addressing the long-held belief that a child’s intelligence is largely inherited from the mother, Dr Sikolia Wanyonyi, a consultant obstetrician, gynaecologist and Foetal Medicine Specialist at Aga Khan University Hospital, says intelligence cannot be traced to a single parent.
“Intelligence is a mix of many things,” Dr Wanyonyi told Nation Lifestyle . “There is the genetic part, the environmental part and the social bit. It is not just one factor that determines how intelligent a person becomes.”
According to Dr Wanyonyi, a baby may be born with a certain genetic predisposition, but how that potential develops depends heavily on conditions during pregnancy and early life.
“You are born with a certain predisposition depending on how you grew up in the womb, which is a very important environment,” he explained. “Then after birth, how you are brought up, what you eat, the kind of stimulation you receive, the schools you go to and the people you interact with also shape intelligence.”
While genes from both parents contribute to brain development, Dr Wanyonyi said the maternal environment during pregnancy plays a critical role in how the brain forms.
“The health of the mother during pregnancy plays a key role,” he said. “Conditions that affect nutrition, the growth of the baby, infections, fevers and poor pregnancy outcomes can all affect neurodevelopment.”
He added that complications such as premature birth, delayed delivery and poorly controlled medical conditions—such as high blood pressure—may interfere with brain development in ways that later influence learning and memory.
Brain development, he noted, begins early and continues long after birth. “The brain starts forming as early as eight weeks in the womb, and its complexity keeps changing throughout pregnancy,” Dr Wanyonyi said. “It does not stop growing at birth. Development continues through early childhood, with the first two years being especially important.”
Because of this extended period of growth, intelligence remains highly sensitive to environmental factors well beyond pregnancy. “The in-utero environment is critical,” he said, “but what happens after birth—nutrition, stimulation, health and care—also matters greatly.”
On common concerns raised by expectant mothers, Dr Wanyonyi said many are grounded in medical fact rather than myth. “Nutrition, smoking, alcohol use and infections during pregnancy do influence a child’s growth and development,” he said.
For parents worried about their child’s future cognitive development, he advised focusing on overall health rather than genetic shortcuts.
Parents who are worried about their child’s future cognitive development should focus on overall health rather than genetic shortcuts.
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“During pregnancy, good nutrition, healthy lifestyle choices and proper antenatal care are key,” he said. “After birth, the first two years remain very important. Good nutrition, stimulation and overall child health go a long way in supporting brain development.”
Taken together, Dr Wanyonyi’s explanation challenges the idea that intelligence is inherited from the mother alone, showing instead that it is shaped by shared genetics and a long chain of biological, medical and environmental influences that begin in the womb and continue through early childhood.
From a genetic standpoint, intelligence cannot be attributed to one parent or traced to a single gene, according to Dr Syokau Ilovi, a physician and geneticist.
“Intelligence is not so straightforward,” Dr Ilovi said, explaining that while children inherit genes from both parents, cognitive ability is influenced by many interacting factors. “We inherit genes for everything, including intelligence, from both parents, but not in a predictable manner.”
She noted that intelligence is shaped by both genetics and environment, with environmental influences beginning during pregnancy. “It has both genetic and environmental components, and the environment starts from the womb,” she said.
No single gene determines intelligence, she added. “It is influenced by very many genes, from both parents,” noting that some genetic variations may also arise independently rather than being inherited.
Dr Ilovi dismissed claims that mothers contribute more to intelligence because of the X chromosome, saying such arguments oversimplify a highly complex process. “You can’t attribute one trait like intelligence to one parent or one gene,” she said.
She cautioned against the misuse of genetic science in public discourse. “Genetics should not be used to advance or sideline people based on certain traits,” she said, warning against narratives that suggest humans can be engineered or ranked intellectually.
Instead, she urged a shift in focus toward nurturing environments. “We cannot change our genes,” she said, “but we can alter the environment to allow people to achieve their full potential.”
