My parents and grandparents were all Republicans. However, the Republican party they supported is not the Republican party of Ronald Reagan or George W. Bush.
I don't think people should pigeonhole themselves as being "a" this or a "that." Molly Ivins eloquently spoke about this categorization of people. "One should view each issue separately."
Look at the historical perspective. Those "horrible" liberal movements brought us scientific achievement, enlighted thinking, and promoted the American Revolution. Much of what America's Constitution is based on--is liberal thought. Liberalism brought an end to slavery, gave us civil rights and women's suffrage, worker's rights, environmental protection, the New Deal and end to the Great Depression.
Even Republican politicians have held liberal beliefs. Many of Lincoln's policies and viewpoints would have been considered "liberal." Teddy Roosevelt was an fervent conservationist and engaged in trust-busting campaigns (please, Republican Party, go back to Teddy, not Reagan).
Eisenhower enabled the funding for our interstate highway system (socialism?) and prophetically warned us against the the "military-industrial complex" in his farewell address. Juxtapose this against PNAC and neo-conservative ideology. Even Nixon created that "liberal" EPA.
JFK summed it up best:". . . if by a liberal they mean someone who looks ahead and not behind, someone who welcomes new ideas without rigid reactions, someone who cares about the welfare of the people - their health, their housing, their schools, their jobs, their civil rights, their civil liberties . . . if that is what they mean by a liberal then I am proud to be a liberal."