How did my moms hair become wavy?

Her hair was always stick straight, and even when it was short it was still completely straight, but the other day she cut about 4 inches off (it was down to the middle of her back and now it’s down to about 2 or 3 inches past her shoulders) and it got really wavy. Could it have something to do with her age? (she’s 45) like hormones?

It looks awesome btw.