High bp reading at 18 years of age

Patient: Hi, im a male 22 years old. when i was 18yrs old i had a high bp readings of 150/80 and 140/80. I dont know if im stressed of what. i went to the doctor and all my blood test are normal except for high cholesterol. my urinalysis also came normal. my father have hypertension. And now my bp is always at 120/70-80 after a diet and aerobic exercise. what is the cause of my high bp reading?now my blood test also are normal except again for the high cholesterol.