If such a thing as a normal childhood can be had in North Korea, Joseph Kim had it. He lived with his father, mother and older sister in Hoeryong, a city that benefits from being the birthplace of Kim Il-sung’s first wife.

There, young families had normal goods and services: a grocery store, a barber shop, an ice-cream parlor. At the end of each day, the neighborhood children would gather around the television and gorge themselves on popcorn and candy.

What Kim’s family did not know was that Hoeryong was, and remains, home to a maximum-security concentration camp, one of six the country is known to run.

As he writes in his new memoir, “Under the Same Sky: From Starvation in North Korea to Salvation in America” (Houghton Mifflin Harcourt), Kim and his family believed that they wanted for nothing.

“We were all alike,” he writes, “one big North Korean family, or so it seemed to me.”

The great famine

When Kim was nearly 4 years old, his father, a respected member of the Workers’ Party of Korea, was so successful that he was able to build a house for his young family. It was 1994.

Kim was enrolled in kindergarten, which children attend for two years. There, he learned about the Great Leader Kim Il-sung, and the importance of constant, daily worship. Every North Korean was to have a framed picture of Kim Il-sung and his wife in their homes.

“You could be sent to a prison camp for allowing dirt to gather on Kim Il-sung’s portrait, or for putting it behind cracked glass,” Kim writes. The first thing his father did every morning was to carefully clean those frames.

The children also learned about America, mainly through illustrations. Teachers showed their students drawings of American soldiers spearing pregnant North Korean women with bayonets and marching them into gas chambers.

“I held my breath,” Kim writes, “as the teachers explained that Americans had come to our country to massacre Koreans for no other reason than they liked to . . . the only people who stopped the Americans from coming to my country, our teachers said, were Kim Il-sung and the soldiers of North Korea.”

On July 8 of that year, Kim Il-sung died, and not long after — unbeknownst to North Korea’s citizens — Russia stopped subsidizing the nation with food and fertilizer. Then, in 1995, biblical rains and flooding washed away what few crops grew. What little there was of the electrical grid went out.

The nation plunged into a great famine. Within weeks, Kim’s father was unable to feed his family, and his mother was ripping up any plant she could find, edible or not, and force-feeding it to Kim and his sister.

“Your body knows when it’s eating something that’s not food,” he writes. “Your belly is temporarily full, but you can tell no nutrients are flowing to your limbs, that there’s no fat to make your taste buds happy.”

The deprivation was sudden and severe. A next-door neighbor’s grandfather died of starvation. His parents began fighting brutally over how to get food; his father refused to engage in bribes or the black market, believing such things morally wrong. His mother was in agony: “You’re sacrificing your own children!”

She sold her wedding dress to buy what little food was available. “We were dying,” Kim writes. “Our eyeballs pushed from their sockets, or so it seemed. Really, our faces were just growing leaner. We had little energy for playing or reading books or anything else.”

By spring 1996, the family’s lone daily meal was a handful of weeds, but some days, they only had tiny sips of water.

Kim’s mother went to stay with her own parents. His father decided their best hope was with his brother, who lived near Pyongyang and was a major in the Korean People’s Army.

They traveled by train, and a journey that should have taken less than 10 hours took them three weeks, each car stuffed with the starving and unwashed, no room for anyone to move.

“People lay in the aisles of the cars, too weak to lift their heads for morsels of food; others were taken out to the fields on either side of the railbed and left to die,” Kim writes. “As we passed stations, I saw corpses piled up outside them, people who’d been waiting and had expired in the heat.”

The escape

The family, whether together or apart, was never welcome at one place for very long. As food became ever more scarce, extra mouths were a potentially fatal liability. Kim writes of seeing one relative, an older woman, sneaking some of the very little food in the house and begging Kim not to tell — her own son had once caught her in the act and nearly yanked out her teeth with a pair of pliers.

Dogs vanished from the streets; so did rats. After even vermin became scarce, stories spread about people killing and eating their own infants and selling their children for food — stories Kim believes to this day.

Kim’s father sold half of the house for a week’s worth of cornbread, and after that ran out, he walked six hours to beg a cousin for food. The cousin refused.

That was the end for Kim’s father. He began decompensating rapidly, screaming all day and all night in agony. Doctors were selling their meds on the black market, and they wouldn’t treat patients unless they were given a full meal.

It took two and a half months for Kim’s father to die. At his burial, Kim’s mother announced that she and his sister would be going to China; she had hired a broker to smuggle them out. His mother would eventually be caught and put in prison, and he later learned that she had sold his sister to a Chinese man.

Kim was 12 years old. He spent the next three years bouncing between various relatives, but at times he lived on the streets or in a detention home for young boys and girls, where he would hear the screams of children being raped by the guards.

Yet security was lax, and after several months, he successfully ran away. With no family and no food, he did what had previously been unthinkable: One cold winter night, he snuck across the frozen Tumen River into China — one of the most common ways North Koreans attempt to escape, and one the government tries to discourage by telling its citizens that the water is laced with 33,000 volts of electricity.

Sold by Stallone

Once Kim crossed the river, he hid in an abandoned house for six days. Finally, he found a church — an elderly Chinese woman told him to look for crosses, because those were markers of safe places. Kim didn’t know what a cross was or what Christians were, but he did as he was told, and he wound up at the Tumen City church.

There, he was plugged into an underground network of Chinese Christians, headed by a pastor who helped North Korean refugees make it out of China.

The pastor became one of the first people Kim truly trusted. He helped Kim stay out of sight, bought him new clothes so he wouldn’t stand out and placed him with an older woman who needed help around her apartment.

After a few months, a missionary came to the church with a special offer for Kim.

“Would you like to go to America?” she asked.

“My immediate response,” Kim says today, “was ‘NO.’ I was so brainwashed that it came out of my mouth immediately.”

He knew little of what was going on in the world. His understanding of 9/11: “I heard that two really tall twin buildings collapsed. I knew it was in America, but I probably didn’t know it was in New York.”

Still, Kim was encouraged to reconsider. He was shown a Sylvester Stallone movie and couldn’t believe what he was seeing: “Stallone … opens the refrigerator and takes out bread and a bottle of wine. He eats the bread and drinks the wine and gets up and leaves. This was astonishing. America was so advanced, he didn’t have to wash his own dishes,” Kim writes. “America was limitless, I decided. I wanted to see what it was like.”

Kim was taken to a shelter in Yanji that was partly run by an American nonprofit called LiNK (Liberty in North Korea). After two months, a young American man named Adrian introduced himself to Kim and explained that he would be taking Kim and two other boys out of China and helping them get to America.

First, Adrian had to make the boys seem more Chinese — aggressive, rowdy, modern — than the deferential and scared North Koreans they were. He taught them how to roughhouse, how to use slang.

He took them out to fast-food restaurants. He exposed them to Western culture and humor.

“You know how you look, Joseph?” Adrian asked one day.

“Trendy,” Kim said, gesturing to his suit jacket with cotton pants.

“No, you look like a North Korean refugee.”

“I was shocked!” Kim writes. “This was my coolest outfit.”

Adrian bought the boys new clothes and told them to stand up straight — they had spent months hunched over, trying not to be noticed.

And then, suddenly, Adrian hustled them in a taxi; they spent days on the run, hopping from hotel to hotel until finally, one night, Kim found himself driven not to the airport but the US Consulate. He would live there for four months before making it to America.

If he can make it here …

Kim was met by a social worker when he landed and placed with a foster family in Richmond, Va.; Catholic Charities sponsored him. He was 17. He barely spoke English, and in the cruelest of ironies, his foster family had unusual and strict rules when it came to food: They kept the refrigerator empty, locked everything up and forbade anyone from eating except at regular meals.

“I couldn’t understand why I’d traveled from China,” Kim writes, “only to end up starving in America.”

He called his social worker; horrified, she immediately placed him with another family. On his first day with his new foster mother, she opened her fridge and said to him, “Joseph, this is your home and you can eat whenever and how much you want.”

Kim assimilated remarkably quickly, and after graduating high school at 21, he decided to move to New York. He has heard that his mother remains in prison for attempting to escape North Korea, and he has no idea where his sister is. “I do hope my mom is still alive, and I hope my sister is somewhere in China with a great husband,” he says.

Today, Kim is 24 years old, and though years of malnutrition set him back academically, he’s just been accepted to Bard and American University in DC. He loves red meat and whiskey and Tinder.

He would like to someday work for an NGO and help other North Koreans but hopes always to stay in New York, which he chose for a very specific reason.

“I was afraid that I couldn’t stand on my feet in American society,” he says. “I was pretty spoiled: I had food and clothing provided. All I had to do was go to high school. But at graduation, I was doubting myself: Did I have the skills to survive? And someone told me, ‘If you can survive in New York, you can survive anywhere.’ ”