Help! Late 70s-mid 80s short scifi story about 2 peaceful aliens who adopted 2 human kids and separated them when they fought?

[JessFran]

Help please! I'm desperately trying to remember the title and/or author of what was probably a Late 70s-mid 80s scifi short story collection. One story in there was about 2 peaceful but emotionally devoid aliens who adopted 2 human babies and separated them for years when they fought as toddlers. I read it in the library as a kid in the early 90s, but the hardcover book looked like it was probably 10 to 15 years older. Any help would be much appreciated!