UJ expert talks about connecting Nature and Nurture

​​What makes us who we are? This question has been debated since the time of the Greek philosophers, and two schools of thought have emerged – ‘Nature’ refers to the idea that our genes determine who we are, while ‘Nurture’ suggests that we are shaped by the environment. However, it is now known that these two aspects work together to define our characteristics, according to Dr Gerrit Koorsen, a Senior Lecturer in the Department of Biochemistry at the University of Johannesburg.​​​

Speaking at a public lecture, Dr Koorsen said that Genetic information is spelled out by the ‘letters’ encoded in DNA. “In total, 4 billion letters spell out the human genome; this requires 2 meters of DNA to be rolled up into the small nucleus of a cell that is barely a hundredth of a millimetre in diameter,” said Dr Koorsen. He highlighted that the process of packaging this entire length of DNA into the nucleus presents a challenge for the cell in terms of accessing genetic information – only those genes that can be accessed will contribute to our characteristics, whilst those that are packaged away might as well not have been there. “It is at this level that our genes (‘Nature’) and the environment (‘Nurture’) interact, since our diet and lifestyle affects to what extent genes can be accessed,” he added.

The branch of biology that studies exactly how this happens is called ‘epigenetics’. If the wrong genes become accessible at the wrong time during a cell’s life, diseases like cancer, autoimmune diseases, neurological disorders and diabetes may develop. Dr Koorsen emphasised that it is important to make healthy lifestyle choices to protect ourselves from diseases. “Smoking should be avoided and a diet rich in folic acid and other B-vitamins, as well as vitamin D (and avoiding excessive consumption of alcohol and salt) helps that just the right genes are active in our cells. Regular exercise is also beneficial – in fact, exercise has a beneficial effect on 7,000 of the 22,000 genes in our cells,” Dr Koorsen said.

Our genes are particularly vulnerable when we are developing in our mother’s womb; therefore a mother’s diet and lifestyle during pregnancy is very important to ensure the health of her child. Surprisingly, a father’s diet and lifestyle before conceiving a child is also important and has far-reaching consequences not only for his children, but quite possibly also for his grandchildren. In fact, studies suggest that a grandfather’s diet and smoking habits at the age of 9-12, a time in a boy’s life when his genes are particularly sensitive to the environment, might affect the health of his grandchildren.

Moreover, it seems that not only our diet and lifestyle, but also our emotions and behaviour might influence the health and happiness of our children and grandchildren. We are indeed the guardians of our own genes and the responsibility rests firmly on our shoulders to make the right diet and lifestyle choices to ensure not only our own health, but also the health of our children and grandchildren.

The public lecture was hosted by the faculty of Science, on Monday 4 August 2014, at UJ Kingsway Campus Auditorium.

  • Dr Gerrit Koorsen obtained his PhD in Biochemistry at the University of Cambridge in 2006, having been awarded a Gates Cambridge Scholarship. Upon his return to South Africa he worked at the CSIR (Pretoria) after which he joined the University of Johannesburg in 2008. He is currently an NRF Thuthuka grant-holder. His research focuses on the structure and function of human linker histones, the proteins that facilitate the compaction of DNA in the nucleus. Dr Koorsen is a Senior Lecturer in the Department of Biochemistry at UJ.​
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