Which of the following diseases is not hereditary?

1. Analyze the question You are asked to pick the disease that is NOT hereditary, meaning it is not passed from parents to children through genes.

2. Explain the concept

• Hereditary (genetic) diseases are caused by faulty genes or chromosomes passed from parents to offspring.
• Non-hereditary diseases are caused by external agents such as bacteria, viruses, fungi, parasites, or poor nutrition. They are acquired through contact or infection, not through genes.

3. Go through the options

• A. Albinism: A recessive genetic condition. The body cannot produce melanin, so the skin, hair and eyes lack pigment. It is hereditary.
• B. Scabies: A skin infestation caused by the itch mite Sarcoptes scabiei. It spreads through close skin contact or shared clothing and bedding. It is not inherited, so it is not hereditary.
• C. Haemophilia: A sex-linked recessive disorder carried on the X chromosome. The blood fails to clot properly. It is hereditary.
• D. Colour blindness: Also a sex-linked recessive trait on the X chromosome, and more common in males. It is hereditary.

4. Answer Only scabies is caused by an external parasite rather than by genes, so the correct option is B.

5. Exam tip Sort diseases into two groups:

• Genetic: albinism, haemophilia, colour blindness, sickle cell anaemia.
• Acquired: scabies, malaria, cholera, typhoid, ringworm.

If the cause is a germ, mite or parasite, it is not hereditary. If it involves a gene or chromosome, it is hereditary.