Curiously, this is something parents are often on the lookout for with their kids - especially younger and less verbal kids. Watching for physical and emotional queues is the difference between knowing when your kid is genuinely upset and just hungry or sleepy. The tenor of a wail can be the difference between “I’ve lost my ball under the couch” and “I’ve seriously injured myself, get me to a doctor asap”. You’ll also notice little kids adopting coping mechanisms - self-soothing by sucking on a hand or clucking a toy can indicate stress even if your child isn’t crying. Flinching from a seemingly harmless object can indicate some kind of pain or trauma (recoiling from food because you’ve got a sore throat, flinging a book because it has a scary picture, etc).

Kids get older and they start learning how to read queues from their parents in turn. And that’s a normal, healthy way to grow, even if what you’re discovering about your family is that they’re chronically stressed or ill-tempered.

“I noticed my mom was upset, so I tried to cheer her up” is an emotional development you should want to see in your children. Because you’re going to be around people who are upset the older you get. And developing empathy is a good thing precisely because it means you’re looking outside yourself and recognizing others as people like yourself.

In theory, it sets off a positive feedback loop. You’re grumpy, and your parents notice, so they try to cheer you up. They’re grumpy, and you notice, so you try to cheer them up. And the net result is less stress, more love, and a stronger bond between family members.

Empathy is a double edged sword, it’s true. The difference that makes a difference is the emotional maturity of the parents.