# Explain how a child can inherit a genetic disorder from two parents who do not show any symptoms of that disorder.

> WJEC GCSE Biology (Wales) — 2.3.2 Inheritance · Explain · 4 marks

> Some genetic disorders are caused by recessive alleles. A couple, neither of whom has the disorder, are surprised to find that their child has been diagnosed with a recessive genetic disorder.

## Mark scheme (4 marks)

1. Both parents carry the recessive allele for the disorder
2. Parents do not show symptoms because they also carry the dominant allele
3. Each parent can pass either the dominant or recessive allele to the child
4. Child inherits two recessive alleles (homozygous recessive) and therefore shows the disorder

## Related

- [Revision notes for WJEC GCSE Biology (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-a-child-can-inherit-c11c2cef) · Published by Druglandscape Ltd.