Can lack of exercise and constant stress cause high bp? all other tests for heart problems, kidney problems and blood problems have come back normal?

Genes and kidneys: Your genetic background and your kidney health are far more likely culprits. Your profile says you're 20-if that's correct, you need a good evaluation for possible causes as essential hypertension, which is the cause in 90% of people, doesn't usually start so early in life. Serious obesity, if present, is an important risk factor.