LB- In the case in the Tanach, the problem was that he didn’t want to get married at all, not that he didn’t want to marry a specific person. That is completely different. Also, he was a man, and men have a chiyuv to get married and women don’t.
I disagree with this idea that it is a lack of bitachon to take heriditary factors into account. You have to be rational about it, and of course, you can’t refuse to marry anyone who has something in their family that could possibly be hereditary (that would kind of limit your choices to 0).
However, if it is known that there is a particular issue in that person’s family, and it is known that it is something very hereditary (and since we are talking about emotional issues, one must also take into account, the possibility of the particular issue being passed down through “nurture” as well as “nature”), it is responsible and appropriate to consider if this is something that you, personally are capable of dealing with.
There is a reason why Dor Yesharim has haskamos from Gedolim.
That being said, of course, one has to have bitachon and can’t go crazy about hereditary factors. They should consider carefully if this person is someone who would be worth marrying despite whatever risks are involved to their future kids, and if they would end up regretting not marrying the person.
But there are two sides to the equation, and it is only responsible to weigh both of them, imho.