A more or less universal truth -
"The more educated I became, the more conservative I became.”
In much the same vein: "If a person is not a liberal when he is twenty, he has no heart; if he is not a conservative when he is forty, he has no head."
This quote (or some variation of it) has been variously attributed to different people from John Adams to Winston Churchill.
Thomas Jefferson
allegedly wrote in a 1799 journal a quote -
allegedly (again that word) attributed to John Adams - that "A boy of 15 who is not a democrat is good for nothing, and he is no better who is a democrat at 20."