In the radio and music industry, it's understood that people establish lifelong musical preferences in their teens and early 20's. Nate Silver says this may also be true of political preferences. Looking at new Gallup data on partisan identification by age, Silver tried mapping it against the question: "who was President when you turned 18?"
As it turns out, "the popularity -- or lack thereof -- of the President when the voter turned 18 would seem to have a lot of explanatory power for how their politics turned out later on".
In general, however, this points toward the idea that partisan identification -- while not exactly being "hard-wired" -- can be quite persistent as the voter moves through her lifecourse. Voters who came of age during the eight years of the Bush Presidency are roughly eight points more Democratic than the rest of the country; that advantage could be worth an extra point or two to Democrats throughout the next half-century.
As Kristen Soltis has pointed out here recently, "young voters began abandoning the Republican Party long before Barack Obama was even a serious contender for the presidency. Those pinning the Republican Party's poor fortunes among young voters on the Obama candidacy miss the source of the problem and certainly underestimate its severity."
Lesson: Republicans had better become more appealing to young people, because patterns established in youth persist for life.