Help With Creating Custom Infant Clothing

I just recently started making cc so I'm fairly new and am a little bit confused on certain things when it comes to creating custom infant clothing.

I have read the tutorial provided on this site but the one thing I'm confused most about is how in the comments its stated that although there is only one DST file for certain skin tones that it can be used for both genders. I've seen creators make custom clothing based on each skin tone and gender.

So you could have a medium skin boy clothing option and a medium skin girl clothing option in your game at the same time for example. How would you go about doing that? Because wouldn't changing the one DST file change the clothing for both genders making the outfit the same for both?? How would you customize it per gender per skin tone?

I'm sorry if this makes no sense I'm not really sure how to word it best and English is not my first language.