Admiring a model train display takes the utmost focus, as any gung-ho "modeler" at the 21st annual National Train Show will tell you.

So does tinkering in the playpen, if you're one of the many captivated children at the trade exposition, which concludes today at the Sacramento Convention Center.

While adults gape at the picturesque, motorized and finely detailed dioramas, their little ones are happy to chug away with Thomas the Tank Engine and his wooden pals.

Randy Keskeys of Sacramento is not a modeler. Yet he found himself chaperoning in the playpen.

"I'd only like trains if I were riding one to the Swiss Alps," he said.

Keskeys brought his 7-year-old son, Ian, to the convention for some male bonding, away from Ian's two sisters. He said that Ian has been obsessed with trains since infancy.

"When Ian was a baby, and he'd see a train going across the tracks, he would cry as soon as he couldn't see it anymore," Keskeys said.

As Ian grew older, he couldn't get enough of father-son outings to the California State Railroad Museum. Keskeys said he became a member, having gone so often that his iPod earphones substitute for the audio tour's devices.

As Keskeys gamely reclined on a folding chair, Ian appeared lost in thought next to a detachable 3-D puzzle.

"These kids are silently focused on the trains – until they bump into some other kid," Keskeys said.

He suspects that Ian's lifelong attraction to trains "must be genetic," since his maternal great-grandfather was an engineer aboard one.

The genetic influence is less distant for Cade and Cort Wilkerson, ages 6 and 5, respectively, from Fair Oaks.

Their father, Ryan, a website developer, has been a hands-on modeler for 20 years. He exposes his sons to the pastime at every opportunity, stressing how educational it can be.

"We enjoy different facets of the hobby," Wilkerson said. "There's a casual and an extreme, and I fall somewhere in the middle … I hope."

As he took turns lugging Cade and Cort from one miniaturized track to the next, Wilkerson quizzed them patiently on the various components of a locomotive.

"What goes in tank cars?"

"Anhydrous ammonia," Cade answered without hesitation, as he apparently has since he was 3.

"And?"

"Propane," he said.

Not to be outdone, Cort knew that the yellow engine traveling around one of the hypnotizing layouts was an "SD70M" model.

Like any self-respecting modeler, Wilkerson identifies himself with a preferred building scale, railroad, and era. (N, Southern Pacific, 1990s, for the curious.)

Wilkerson said he spends relatively little on the hobby, about $1,000 per year. And he hardly qualifies as a "rivet-counter," the playful jargon, he said, for a stickler for details.

Wilkerson doesn't limit his fascination with trains to the realm of prototypes.

He takes the boys on "train-chasing" adventures. They watch videos together.

Lessons range from reading the trains' side panels, handling fragile plastic objects with care and saving up birthday money for kits.

"If they're watching the trains go by, they might as well learn something," Wilkerson said.

He thinks the activity is good for his children's memory, identification skills and historical awareness.

For all his fatherly encouragement, Wilkerson is "pretty sure" his two towheaded tykes will lose interest at some point in their childhood.

"Hopefully they won't turn on me when they're older," he said with a laugh. "It's a part of people's childhood, and they get back into it later in life."

Tom Draper, chairman of the National Train Show, said he followed that very pattern.

Enthralled by trains as a youngster, he drifted over to sports and dating, and then to his career at Motorola. Draper said he rediscovered his earliest love after he had enough disposable income, and it truly "blossomed" upon his retirement.

"You never know what's coming down the road – or the tracks, in this particular case."

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