Each of our genes is a copy from our mom or our dad so, if there is a mutation in one of these genes this can be passed on from parent to child along with the rest of their genes. Small inherited changes can make big differences to our bodies, for example, the most common mutation to cause cystic fibrosis is the loss of three letters in a gene called CFTR. Even though mutation is common, inherited diseases are very rare so, this is because inherited diseases are often recessive which means that our person must have two copies of a mutated gene to get that disease.
It depends where the gene is expressed. If a gene is only expressed in the testes, then it will only probably cause male infertility. Similarly, a gene expressed only in the ovum causes female infertility. If the gene, however, is expressed in the testes and other tissues in the body, then you’re more likely to get a syndromic problem where you might get deafness and male infertility, or other such diseases.
