I think they test your partner and your DNA to see whether ok or not.
MrAlson
Oh . . . I see. . thxs alot
Sakuraflower
stupid la...u wan to marry the person still see the surname!!!!
Othello_Red
Put it this way. Unless the other person is relatively close to you in terms of lineage, sibling, immediate cousins, etc, it is unlikely that anything bad will come out of it.
Checking your chromosomes might be one way of making sure that the risks of having a child with hereditary problems are reduced. But you must remember after the knowledge and the percentages, its will become and live probability demonstration at the end of it, so simply put, shit might still happen.