But they didn't want to just write a check.
"I want to see the numbers. I want things to make sense. I want them to be sustainable," Rex says.
They are part of a growing trend in philanthropy — people who view their donations not only as gifts, but as investments.
In Rwanda, an impoverished African country where most people make less than $2 a day, the Aminis helped a group of women expand a soap-making factory. But first, they made sure the money would be put to good use.
"We had no earthly idea how much things should cost," Rex says. "How are we going to demand accountability? And Geneva Global provides all that."
Geneva Global is a for-profit company that offers independent philanthropy advice.
"Investment advisors for international philanthropy is not our tagline, but it's actually a good description of what we are," says Steve Beck, CEO of Geneva Global.
Their average donor gives hundreds of thousands of dollars. For about a 15 percent fee on top of that, Geneva Global helps find worthy charities and then provides clients like the Aminis detailed analysis of them.
"And then we track the results along the way, much the way people track their investments," Beck says.
That includes telling them when their investment is a bust, which happens in nearly 20 percent of the cases. It's called "performance-based" philanthropy.
"I think these women are very invested in growing this project," Deborah says of the women at the Rwandan soap factory. She adds that she's "absolutely" willing to be invested.
Because of the Aminis' contribution, the women at the Rwandan soap factory have been able to increase their production 50 percent in the past year and hire more workers.
And seeing those results have made the Aminis even more generous. Their latest gift: a new school. Their charitable investments may not have brought them a financial profit, but the Aminis are seeing much deeper rewards.