Twice a day in our house, we turn on a projector that casts cartoon music videos on a blank stretch of wall. The songs are catchy and bright and usually keep our toddler captivated for the amount of time we need him to hold still. “There are no monsters who live in our home,” goes one of my favorites. “There’s only me and my family who live in our home / ’Cause there are no monsters that live here.” Up on the wall, two healthy-looking cartoon children learn not to be scared of the dark, while my son clutches my forearm and breathes dutifully into a mask. Sometimes he spots something familiar — an animal with a noise he can make, a color he knows how to say — and rushes to point it out, only to have his voice muffled by medical equipment. Unlike the home in the song, ours does have a monster, one that doesn’t hide under the bed or in the closet. Half of it lives in my husband’s DNA, half in mine. We’re still figuring out what the whole thing looks like, but we do know it’s coming for our son. In lots of ways, it’s already here.