Paternal lifestyle and epigenetic inheritance
Naldo G
In our biology classes we learn that we get half our DNA from our mothers and half from our fathers. But when you look at how the life of a parent affects children, mothers were always the focal point. It all made sense – the mothers were always the ones carrying the baby, so whatever they consume, drink, or endure will directly influence the child. The fathers, however, were assumed to be simply contributing the sperm – a small package of genes that was either good or bad but could not be altered by whether he ate rubbish food or was significantly stressed at work. This concept is now totally changed by a new field of science known as epigenetics. Epigenetics studies how lifestyle and surroundings can make changes that influence how genes function but do not change the DNA code itself. In this essay I will be arguing that a father's diet and stress levels prior to having children actually cause epigenetic changes that affect his children's health and development. However, the influence of has limits and is often overpowered by the mother’s role and other factors. To explore this, I will use ideas from Nessa Carey’s book, The Epigenetics Revolution , which explains these complex ideas in a way that’s easier to understand. So, given that sperm is tiny and was thought to contain only DNA., how does data about the lifestyle of a father appear in his sperm? The answer is in some sneaky processes that function as a biological USB stick, containing additional information. The first of these is known as DNA methylation. This is where small chemical tags called methyl groups get stuck on some parts of the DNA. As Carey (2012) discusses, these tags generally act more like a ‘do not use’ warning, telling the cell to ignore that gene. A bad diet or excessive stress can disrupt the enzymes involved in adding or removing these tags. For example, a high-fat diet can change the quantity of nutrients involved in this process, and more complex or fewer tags are placed improperly. These changed tags then may be passed on via the sperm. The second structure is made up of histones. DNA is not just floating around in a cell; it is wrapped around proteins called histones, like spool and thread. Even in sperm, where so much DNA is coiled up, 5-15% of it is wound around these histones. These histones even have chemical flags attached to them (like tiny flags), and these flags specify how loose or tight the DNA is wound and hence what genes can be read. Stress or diet of a father would change these flags on his sperm's histones. The third and maybe most modern way is through the use of small RNAs. Scientists just discovered that sperm isn't just DNA but is also packed with tiny molecules called non-coding RNAs. These are not present by coincidence – they act as messengers. The research shows that if a father is stressed or eats poorly, the kinds and amounts of these RNA messages in his sperm change. When the sperm fertilizes the egg, it sends these messages along, which can actually control the way the embryo develops. Each of the three mechanisms shows that there is a clear biological way that a father's life experience can leave its mark on his sperm, and eventually on his children.
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