Looking for advice: Mixing different types of yarn?

Hello, fellow crocheters!

Since tomorrow and the day after are holidays, I won’t be able to make it to the yarn shop before then, but I have an urgent crochet project coming up, so I’m hoping for some good advice here from more experienced crafters.
Can I crochet with one strand of sock yarn together with one strand of cotton (i.e., using two strands at the same time, but made of different materials)? A friend of mine said that cotton is quite stiff and wool tends to stretch when washed, so she wouldn’t recommend it. I was hoping that since everything is crocheted with two strands, it wouldn’t matter. Does anyone have any experience with this?
Thanks in advance for your help,
Fränze

Hi, it really depends on what you want to crochet

In the vast majority of cases, sock yarn is a blend of virgin wool and acrylic. It’s stretchy while you’re working with it but retains its shape when washed.
With cotton, it’s exactly the opposite.
It really depends on what exactly you want to make... 

I’m planning to make a “Ponpulli,” with a slight twist—in my case, a turtleneck sweater for a child around 4 years old. However, the front and back pieces aren’t worked from top to bottom, but from side to side (does that make sense???).
Thanks in advance, and I’d love to hear more advice!

Hmm, for something that might not need to be washed very often, I’d definitely crochet with both yarns together… but since it’s supposed to be children’s clothing, I’m very skeptical about that.
I’d probably consider something else instead.

Best regards