Which of the following disorders is linked to genetics?

Sickle cell disease is indeed strongly linked to genetics. It is an autosomal recessive disorder caused by a mutation in the HBB gene that affects the hemoglobin in red blood cells. This genetic mutation results in the production of abnormal hemoglobin, leading to the sickle shape of red blood cells. Individuals who inherit two copies of the mutated gene (one from each parent) will have sickle cell disease.

The genetic basis of sickle cell disease is well-established, which is in contrast to other disorders listed. While asthma, diabetes, and heart disease can have genetic components, they are also significantly influenced by environmental factors and lifestyle choices. For instance, asthma can be triggered by allergens or pollution, diabetes can be linked to diet and exercise, and heart disease risk can be affected by factors like smoking, diet, and stress. In the case of sickle cell disease, it is predominantly inherited and the genetic component plays a major role in its occurrence, making it the most clearly genetic disorder among the options provided.