Rotate your peep, not your string.

Most likely your bow is in spec. Rotating your string 1/2 turn could take your bow out of tune/spec.

It is safer to rotate the peep 1/2 turn and see how that works out.

Assuming your string is newer, you can train your peep to rotate how you want. Click on your release, before you draw back...rotate you peep in the opposite direction that it is turning. 10-50 times doing so will train the peep.

If your string is older, I suggest replacing the string with something like Vapor Trail or Winners Choice. Severe peep rotation is often the first sign of a stretching/older string.

Remember, when you replace your strings/cables, it is important to get a warranty and not just a "if something happens, then I'll take care of it" word of mouth warranty. Honesty is not all it cracks up to be on the internet.

Best of luck!