Genes and You

Most families don’t need to worry about the genetic instructions they will pass on to their children. But in some circumstances the genes aren’t working properly and might cause developmental problems.

Here’s some information that will help you understand genetics and the issues some families face.

Genes are the ‘instructions’ telling our bodies how they should be made. These genes determine how our bodies will work and control many things, for example, what colour your hair and eyes will be, the size of your feet and hands, what blood group you will belong to, how well your hearing will be, and the functioning of your kidneys and heart. We have two copies of each gene and we get them from our parents so we receive one copy from our mother and one from our father. There are many thousands of different genes, each carrying a different instruction. When we have children, we pass on only one copy of each of our genes and they receive the other copy from their other parent.

When a gene does not work properly we call this gene changed or altered. If this happens it means that the gene is no longer able to give the correct instructions to the body. This can sometimes lead to certain disabilities or conditions known as genetic illnesses.

These gene changes can sometimes be passed down from parents, or sometimes they occur for the first time in the individual. When changed/altered genes are passed down in families it can happen in a number of ways depending on the gene involved. The main ways in which they are passed on are called autosomal dominant, X linked and autosomal recessive.

We will talk in a little depth about autosomal recessive inheritance, but to read more about Autosomal dominant or X-linked inheritance please visit our “meaning & definitions” page.

Below are 3 examples of how genes are passed on to the children in a family.

Family 1
Both parents are healthy carriers of the changed gene. Their children will either inherit the healthy gene or the changed gene from each parent and this is at complete random.

When the mother is pregnant there is a 25% chance (1 in 4) that the child will inherit one healthy copy from mum and one healthy copy from dad. This means they will be healthy and NOT a carrier and so will not suffer from the recessive condition and will not be at risk of passing it onto their future children.

There is a 50% (2 in 4) chance that the child will inherit one healthy copy from either mum or dad and one changed gene from the other parent and so will be a healthy carrier. They will not suffer from the recessive genetic condition however as the child has one changed gene so they will be a healthy carrier like their parents and may be at risk of passing it onto their children in the future.

There is a 25% chance (1 in 4) that the child will inherit a changed gene from both mum and from dad and so this child will suffer from the recessive genetic condition. This is because they have 2 copies of the changed gene.