Crazy Hair

When I was younger I had naturally curly/wavy hair. My sister had straight hair that would not even hold curl when you curled it. After puberty her hair became naturally curly and my hair became straighter. Not completely straight but it lost enough the the waves that were left just looked messy and weird. For a few years, I got perms but I've been straightening my hair for years now. Lately, if I just let my air dry, this is what it does:

Not sure what caused it to revert back to its curls, but I'll take it