“I have two kids (ages 6 and 9) and every time I compliment one of them, the other one gets extremely jealous. It doesn’t matter whether the compliment is for something small (‘good job putting all your toys away’) or something big (‘I love how kind you are, it makes me so proud of you’). It’s gotten to the point where I feel like I can’t say anything positive to one of the kids if the other one is around… Is this normal? Please help!”
Jealousy is a completely normal emotional response that persists throughout a person’s lifespan. We just get better at hiding, channeling and sublimating it into more socially acceptable behaviors as we age. While jealousy often has an aggressive tinge to it (“I'm going to steal/get what they have” or “they don't deserve the recognition and I'm going to expose that”), it serves the evolutionary purpose of motivating us to work harder to access the desired outcome—in this case, parental attention and praise. It can also serve to communicate an emotional need, which might be the case if it’s always one child who is expressing the jealousy.
As a parent, you can use that to your advantage. Allow your child who is not receiving recognition to express and feel their jealousy. Then highlight specifically what it is that the other child is getting praise for, and provide pathways for the jealous child to receive the same recognition. (For instance: “Jessie worked really hard on his school project last week and got great feedback from his teacher—why don’t we sit down and look at what homework you have this week and see if there’s anything that you’re excited to work on?”)
When the kids aren't fighting, it's important to establish a family culture of helping each other out, doling out recognition freely and readily and reinforcing prosocial behavior between the kids. For example, you might implement a family marble jar with a group reward at the end (i.e., everyone going out for ice cream), and add to it whenever the kids show teamwork (like working together to clean up the living room).