I would argue it has, but I don't believe anyone could currently understand how, and I think concrete examples (e.g. Height) aren't evidenced enough to be justifiable. If anything, I would argue the reverse of most people--our cultural stability (e.g. 'To be humane') makes us relatively stagnant in terms of evolution. That is, it has affected our evolution by slowing our evolution. If we warred more, I think we would evolve faster (which is one thing Hitler was thinking). It's hard to be sure how we would evolve as a consequence, though, except perhaps violent, strategic, or physical strength tendencies would probably be favored.

Our culture is rooted in fairly conscious decisions. You could argue that these conscious decisions affect phenotype selection, but I doubt they do in any meaningful way, evolutionarily speaking. Phenotypes aren't always expressed, or in obvious ways. Thus, a conscious cultural intention to wipe out any sort of phenotype--such as by defining "what is attractive"--will ultimately always fail. (I mean, I'm pretty ugly and I can still manage a girlfriend from time to time). The genes will always remain in the population. Dominant genes would never be culturally wiped out--people are compulsively conforming, and will favor them. Recessive genes, by nature, may be hidden from direct observation (e.g. Of physical characteristics).

Apparent changes in genetics as a function of culture are much more likely to be epigenetic--the genes express differently (they can be "on or off") as a function of experience, including cultural experience. Just because a culture leads certain genes to be "off" doesn't mean those genes have been wiped out, though.