Parents of identical twins how did you prevent mixing them up especially when they are newborn babies?

One parent I heard about via a friend had one boy vaccinated on his left arm the the other on his right arm so she could tell by where the vaccination mark was which boy was which.

Im not a parent but I knew twins and their mother gave them different coloured hair ribbons they wore each day. Red and blue or pink and blue.

Generally they have distinguishing characteristics. A freckle. A mole. They're usually not the same size, even if they're identical. It's pretty uncommon for the actual parents to not be able to tell them apart, even from birth.

The toenail polish thing would work, just write down which one you put it on!

We put a drop of nail polish on one of them.

I've heard about using nail polish to paint the toenail of one of the kids... Then all you have to do is remember WHICH kid has the painted toe.