Our two youngest children are at each other’s throats.

Simon, 10, and Lucy, 9, are only 15 months apart and sometimes they play together like they are best friends. Lately, they’ve been acting like Republican and Democratic nominees for President in a cage match.

We thought that getting back to school, and immersed among their own friends, would diffuse their antagonism, but it seems like they can’t share a chore or get through a family football game without turning red in the face, or calling names, or stomping off in anger.

The other day, as I picked them up from school, Simon kicked Lucy in the ankle on their walk to the car because she would not yield the bigger of two rocks as a place to sit while they waited (the big rock being obviously preferential and advantageous for waiting). Lucy, for her part, knows how to very effectively wheedle her way under Simon’s skin to raise his hackles.

I got so frustrated when they climbed in the car—I had reached my limit. “What do you think other people think when they see you behaving that way?” I asked. “Do you think they see a family who loves each other?”

I’ve been approaching this conflict by administering correctives, but they’ve been punitive in nature. If they can’t share, neither of them gets whatever it is they both want, for example. This has only built resentment, though, not cooperation—they both blame the other for losing out in the situation.

Things were only intensifying and spiraling into defensiveness, selfishness, and petty bickering. We needed something to change the energy at play between them.

So, I took a different approach. After a day of arguing, they are now required to do something intentionally kind for the other. I told them they could write a nice note, or help with a chore, or surprise each other by being helpful in some way.

Moving away from punishment to intentional kindness has already changed the dynamic. Approaching hostility with generosity seems to break the cycle. They are not sniping at each other, looking for an opening to attack. There is a different spirit between them—lighter, more joyful.

The same thing happens when Stacey and I are on the outs with each other. We’re getting better at recognizing when we are out of sync, and reaching out to the other with a gesture of generosity re-frames the situation. When one reaches out in this way, it allows us to both crawl out of our foxholes and meet in the open ground.

Isn’t that what love is? Love is unconditional generosity, especially in the face of spite and selfishness. This is the love that God displayed in becoming one of us in the person of Jesus Christ. This is the love that Jesus displayed in giving his life for us on the cross. Marriages and families are nourished with this love in the Eucharist. A body broken, blood poured out—in the end, these are the only gifts we have to share with one another, and in the sharing become whole again.

It has been said that family life is the “school of love”—it is the place where we learn to practice love. Siblings learn love from one another, too (in fact, there is increasing evidence to show how formative those sibling relationships are). The most difficult and essential form of love to master is generosity in response to selfishness, and we have many opportunities to practice it in family life and marriage.