I can't say whether it's what makes the difference or it's a natural development, but they 100% for sure do. Both direct instruction and example behavior.

There are many parent who never instruct their kids to care about other people, and those kids turn out fine. The vast majority of what you have to tell a todller is variants of "don't put that in your mouth," and sometimes "stop hitting your sister." I've never heard of an admonition to "be more caring." (Note: that sounds like a heartwarming idea unless you have met a toddler before)