I can guess what the reductionist assumptions are, but I'm not sure who's making them. I've read some material here and there by scientists cautioning people that knowing the order of bases and genes does not tell us how they work or what they do under different circumstances. On the other hand, the media by and large seem to prefer the simplistic mode: tell us your genes and we'll tell you everything there is to know about you, including your thoughts and life history. The latter would be a tempting stance for genetic researchers to pretend to take, since (if believed, as reporters and editors seem to want to do) it would get them much more repute, power, and money.