People with dark skin can experience vitamin D deficiency in northern climates. One of the many symptoms is hypertension.
Some estimates are that you need 10 times more sun exposure to produce the same amount of vitamin D as a person with pale skin.
Agree with the part of constant stress.[0][1] Some full moons ago I took pills that among other effects also had a side effect of increasing blood pressure. Which they absolutely did to me until one day I postponed them in the last minute only to feel the side effect the same way as usual a few minutes later when they should have reached the blood stream.
From that day that side effects disappeared. Our brains plays games with us. About 30%[1] of us seems more prone to this[2] than others.
[0]: context: JulianMorrisons post was downvoted when I commented. I read it as funny, not SJW, and I agree that constant stress seems to be a big issue.)
[1]: See vixen99s explanation for what seems like the dry facts about the link between skin color and hypertension