Hard to say because my hair gets fried and split ends from anything.
I think lost curl is more likely just hair changing than actual outside influences (because my hair's heading back toward 3b after being there in the past, but spending the last few years in 3a Land.) But color is probably most likely of those to do it-though with my hair, the other options all result in far too many split ends and yuck.
The pews never miss a sermon but that doesn't get them one step closer to Heaven.
But at least the pews never attend yoga!