Conservatism isn't caused by fear. I'd agree that there are certainly a lot of "traditional US republicans" that have a lot of fear in their heart, but I don't think it's a causal relationship. If anything it's probably the other way around; conservatism causes fear. Demagogues from the tea-party take peoples misfortune, doubts, and hardships and spin it into a narrative of prejudice, blame, and fear towards others. They know that they won't get votes by saying "sort yourself out" so instead, they scapegoat some other group or philosophy (socialism), it's not called fearmongering for nothing.
Also, I can definitely mirror what everyone saying with it being related to age. When I was younger (I'm currently 29), I was definitely a lot more left. That said, I feel like the major reason for me being so far left in my teens/early 20s was that I was more or less a single issue voter (religion = bad). I still am very much critical of religion and religious institutions, but I've become more layered, mellow and accommodating in my approach, and it's no longer the only issue important to me. I view religion as a type of authoritarian rule, and I'm incredibly sensitive and against any type of authoritarianism.
Right now it just so happens that it's the left that is evangelizing and displaying authoritarianism the most, so naturally, I've been pushed more to the right (or center really). I'd argue that my politics are mostly unchanged and that it's the left that has spun out of control, but that's a separate conversation.