Omg wow! We're like opposite twinsWOAH that’s so interesting! Something similar happened to me, just reversed. When I was 5, 6 years old my hair was pin straight! Maybe the occasional wave but not wavy or curly. Some time in puberty it poofed up and I was walking around with Hagrid style frizz (because I styled my hair as you would style straight hair) and one random day when I let my hair air dry I realised it’s super curly.