Are there some genetic reasons i get gestational hypertension during my pregnancies?

Probably: If you answer this definitively, you will win a nobel. There are lots of theories. A prominent one is that you have a abnormally high level of a protein called soluble fms-like tyrosine kinase (s-flt-1), which makes it difficult for small blood vessels to grow. This protein is connected to hypertension and pre-eclampsia in pregnancy.