The majority of the people voted for Democratic house candidates.
Imagine a state with two districts, each 55% Democratic. That would give you two Democratic seats in the House. If you instead combine them and divide them into two districts such that one is 90% Democratic and the other is 80% Republican, you end up with one Democratic seat and one Republican seat. This is what Republican-controlled states did after the 2010 Census. Without the gerrymandering, the House would now have been Democratic.
The media keep saying that the electorate chose to divide Congress this way, but this is not in fact true. Boehner has even less credibility now to block legislation.
To see this, go to the NYT House map, zoom into one of the Republican states (e.g., Texas, Louisiana), and hover over the various districts. You will see how strangely shaped they are.