Variation

Inheriting mutations

Each of our genes is a copy from either our mum or our dad. If there is a mutation in one of these genes, this can be passed on from parent to child along with the rest of the gene. This is why diseases can run in families.

Small inherited changes can make big differences in our bodies. For example, the most common mutation to cause cystic fibrosis - a disorder where a person's internal organs become clogged with thick mucus - is the loss of three letters in a gene called CFTR.