Did God make Aliens?

Today, the twins & I were discussing how God creates babies inside their mommy's tummies. We talked about how He created both of them in my stomach at the same time. Then, we talked about how He created Nicholas 2 years later. We talked in length about God's different creations, then Samuel surprised me when he asked, "Did God make aliens?"

"No" was not an acceptable answer for him. He actually got upset when I explained that aliens were just pretend creatures, like monsters and ghosts. Maybe he knows something I don't...