A dad’s influence on his kids begins before they’re even a glint in his eye

Genes and inheritance

We know the genes our kids inherit from us are what gives them the colour of their eyes and hair, and influence their height, health and other characteristics. All of those genes — all the information about how to build a human being — are in the sperm and egg that join together at fertilisation. 

As the fertilised egg divides into new cells to form the embryo, the genetic information — in the form of the code in the long strands of our DNA — is copied so each cell has the same instructions.

The genetic code inherited by our kids is permanent. That’s why, if your kids inherit genes that result in things like colour blindness, it affects them forever.

None of our cells use all the information in their DNA. The cells in the embryo divide and grow to become skin, brain, heart, bone, and all the different parts of the body by expressing (using the instructions from) different genes.

Gene expression and epigenetics

Gene expression (whether or not information in the DNA is used) by different cells is affected by things like how the DNA strands are curled up inside the cell, or by chemical ‘tags’ on the DNA which can change depending on things like age and the environment.

These changes to the DNA are known as epigenetic changes, which do not affect the DNA code, just how it is used by the machinery inside the cell. These types of epigenetic changes are the causes of things like the body changes that happen during puberty, or going bald as people get older.

However, unlike our genetic code, epigenetic changes are not permanent. They can be changed by things in our environment, like pollution, or our behaviour, such as how we eat or how active we are.

We used to think that epigenetic changes to DNA in sperm were ‘reset’ during early development, so the only thing children inherited from their fathers was their DNA code. But this way of thinking can’t explain recent evidence that shows things like a father’s age affects his children’s risk of autistic behaviours, or that his obesity might be passed down through generations.

The need to understand how sperm epigenetics influences health across generations

It is possible that epigenetic changes to the DNA in sperm can be passed on from fathers to their offspring.

Researchers from Deakin University’s Institute for Mental and Physical Health and Clinical Translation (IMPACT), the Hudson Institute of Medical Research, Monash Health and Monash IVF, are recruiting male twin pairs to study the impact of diet on sperm quality and epigenetics. The study is being conducted in collaboration with the University of Copenhagen, and Twins Research Australia, and is the first such controlled dietary study in male twin pairs.

“If diet can change both the quality and the nature of sperm, the next step will be to determine whether epigenetic changes are passed onto a man’s future children and how this might impact the health and disease status of the next generation,” said Professor Jeff Craig, form Deakin University.

The researchers are currently looking for male twins aged between 20-45 to register for the three-week study, which will require each twin to eat a different set of prepared meals over the study period. Their participation will add vital knowledge in this pioneering area of biomedical research.

Craig said.  Epigenetic changes to sperm can happen over a short time, so it is likely an intervention could reverse these changes just as quickly. If epigenetic changes in sperm are problematic to the development and health of offspring, the cause could be addressed by campaigns encouraging behavioural change before trying to conceive a child.