This has been happening since the dawn of time but the pace has picked up over the past century. Every time we overcome a genetic trait that impedes survival or reproductive success the result is that the trait becomes more prevalent. Just two examples: The invention of eyeglasses led to an increase in nearsightedness as the almost-blind prospered, and the discovery of insulin caused diabetes to spike as diabetics could survive long enough to have children of their own. I think we'll see a similar rise in cystic fibrosis; when I was a kid the life expectancy of a CF patient was about 15 years but now it's not uncommon for them to make it past 25.
The incidence of nearsightedness varies of the degree of literacy ~ with the effort required to read resulting in a lengthening of the eyball.
Since most Type I diabetics back in the "good old days" survived long enough to pass on their genes, the invention of artifical sources of insulin has not had any impact. Type II diabetics are usually not discovered until past mid-prime by which time they've already passed on their genes. Besides, additional insulin doesn't help them at all.
Best bet on culturally induced genetic change in humans has been the effect of shoes/sandals on the foot.
It's pretty obvious our two smallest twos (and associated bones) have been becoming smaller over several tens of thousands of years since we first started using shoes/sandals (and moving "North").
Otherwise, that's about it~
The cystic fibrosis gene is fairly common because the carriers are resistant to cholera. Similar to the relation between carriers of sickle-cell and malaria, or carriers of Tay-Sachs and tuberculosis. Source: "Guns Germs and Steel" be Jared Diamond.