Although your genetics may make it more likely for you to get sleep apnea, several things make sleep apnea worse in some people.
Being overweight is one of the largest risk factors for sleep apnea. Although all family members may share the genetic risk of sleep apnea, overweight people are much more likely to suffer from it.
Both chemicals cause muscle relaxation resulting in the narrowing and collapse of the muscles around the throat at night.
Smokers are more likely to suffer from sleep apnea, because smoking irritates the upper airway and causes inflammation.
Low thyroid hormone (hypothyroidism) increases the risk for sleep apnea. Hypothyroidism shares many symptoms of sleep apnea, and is similarly under-diagnosed. Symptoms include daytime sleepiness and fatigue, weight gain, nighttime snoring, and depression.
Other medical conditions such as nasal congestion and seasonal allergies can block airflow through the upper airway, which increases the risk for developing sleep apnea.
Although sleep apnea can result in high blood pressure (hypertension), some anti-hypertensive drugs can cause sleep apnea. Similarly, several other drug families have been linked to disrupted sleep, which increases the risk for sleep apnea (e.g. long-acting benzodiazepines, beta-blockers and theophylline).