At 6:30 in the morning, at the end of an upscale San Ramon cul-de-sac, eight-year-old Lucas Clark is waking up. He lies blearily in bed, covers pulled up to his neck, staring fixedly at his big-screen TV. His twin sister, Courtney, and ten-year-old sister, Sydney, put the finishing touches on their school outfits when they aren't darting in to peek at Lucas' cartoons. Their father, Dean, an affable software engineer, shakes his son out of bed, while their mother, Stefanie, assembles breakfasts and lunchboxes and calls for Lucas to come feed the dog.

Chris Duffey

Lucas Clark gets a push from his twin, Courtney.

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A loud humming and the tempestuous drumming of feet on stairs announce Lucas' somewhat grumpy arrival in the kitchen.

"You didn't get dressed yet," his mom chides.

"Go home!" the pajama-clad Lucas says firmly.

"No, we're going to school today," Stefanie says.

"Go home!" he repeats.

"No, we have to go to school."

"I don't!"

Ignoring him, Stefanie hands him the dog bowl. Lucas, still humming, goes to the fridge for the can of food, gingerly smells it, and makes a horrible face. At this, everyone holds their breath. Lucas is famous for throwing up around dog food. Instead, he calmly digs at it with a fork and says "Yuck."

Relieved, Stefanie says, "It's a big deal that he can just say yuck."

In fact, it's a big deal that Lucas can say anything. A year ago, he barely spoke. This morning, he's practically chatty.

"Dog," he announces, plunking the bowl down.

"Sit!" Stefanie prompts helpfully.

"Sit!" Lucas echoes. The golden retriever obeys.