I think it is just the luck of the draw on the same career trophy. I am on my 6th or 7th generation in each of my 5 families, and have passed up multiple proposals waiting for the perfect career match and have not gotten it yet. Once my females hit 40, I marry them off to whomever, so they can start a family. Males I give until 45 or so. I guess it will be one of those pleasant surprises when I do find the perfect match.