My straight hair went curly after pregnancy. Had to learn how to manage curls, test all new products, and get a new stylist. Pain in the butt, but I like my curls now..

A friend of mine had brain cancer - chemo, radiation - and her straight blond hair fell out. Grew back in curly and red!

It’s gotten progressively curlier as I’ve gotten older, but perimenopause accelerated it from a loose wave to full-blown ringlets.

So funny all of the pregnancy responses mention the second pregnancy. That second big dose of hormones must be a common factor.

My hair went from ruler straight to wavy/curly. It was after I had a very high fever from an infection when I was in the hospital after an accident. LOL that a very old-timey nurse came by one evening, very late, and as she was checking my vitals she told me that my hair would go from straight to curly b/c of the fever. Later a younger nurse who had been outside in the hallway came in all upset and told me to ignore the 'old bat' and that it was an old wive's tale. But you know what? I now have curvy and wavy hair.

For your family, OP, I would get in asap to the doctor's office and ask about anything environmental that might have caused it. It is weird and maybe even a little alarming that 2 people (in the same household?) went from straight hair to curly very suddenly.

My hair went from straight to wavy after two kids.

How bizarre. Is there anything you can do to change this or just deal with whatever change occurred?

In my family straight hair turns curly/wavy during puberty.

Yes lots of changes to my hair during puberty (stick straight to wavy) and pregnancy (straighter and dryer).

My hair was thick and straight with just a tad of wave that a blow dryer would get rid of, until my second pregnancy when it changed overnight (or what felt like it at the time). That was 10 years ago and I still look like I got a perm. I didn't realize it had changed right away so I turned into a frizz ball for a few months until my hair stylist made the observation that the texture was different. She had to show me how to style it and what products to use, it was so strange.

My stick straight hair curled during puberty. It was around 1992, and I thought the perm I had gotten just never grew out!

My ringlet curly hair went straight after having two kids. My sister thought I was getting professional blowouts but it’s just hormones.

Hormones can do that.

My stick straight hair got legitimately curly while I was pregnant with my second kid. It went back to straight within a year of giving birth.

This is very odd. For two people in our family their hair has gone from natural wavy curls to almost tight course/curly hair and straight/fine hair to curly ringlet hair in the past year. No changes between seasons. Is there something in the water that can do this? No change in another person and slight increase in curliness in another one.