What are the causes of high blood pressure?

My partner is always cool and calm but his GP told him today that his blood pressure was slightly high.

a high salt intake and lack of excersise, junk food , tv dinners and alcohol

stinger ........... iam sorry but having sex with high blood pressure can put you at risk of having a heart attack ------ saying that it depends on how high the blood pressure is

stress
Age. Over time, the number of collagen fibers in artery and arteriole walls increases, making blood vessels stiffer. With the reduced elasticity comes a smaller cross-sectional area in systole, and so a raised mean arterial blood pressure.
High salt intake
Sedentary lifestyle
Tobacco smoking
Alcoholism
High levels of saturated fat in the diet
Obesity - In obese subjects, losing a kilogram of mass generally reduces blood pressure by 2 mmHg.
Stress
Low birth weight
Diabetes mellitus
Various genetic causes
Occupational, aircraft and roadway noise exposure
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the food you eat or how you are felling work load
Anger, Short temper, Salty foods, Too much salt on your french fries, Greasy foods, Fast food such as McDonald's, Wendy's, Burger King.
Mine is quite high. So is my brother's. Both of our parents had high blood pressure. My brother leads a healthy, physical life (I don't so much) but we are both in the same position with blood pressure.