While the Summer of Love was in full swing stateside, young sergeant Allen Thomas was shipped off to Korea. Little did he know, however, that it was the start of an odyssey that would span decades.

September 10, 1967 was likely one of the happiest days of Allen Thomas’ life. After all, his partner, Connie, had just given birth to twins – a boy, named James, and a girl, named Sandra. What’s more, a year later and Thomas had married Connie and adopted the son she’d had in a previous relationship. But the good times were, sadly, not to last. That’s because a series of events in the following years would blow Allen’s life apart and send him on a journey that can only be described as epic.

The story begins, though, in 1966, when Thomas departed New Hampshire for South Korea. He was just 19 years old at the time, and he was sent as a fresh-faced G.I. to Korea’s demilitarized zone – where relations between North and South were tense.

There, he would work on military helicopters. But that’s not all he did. Yes, the bright lights of Seoul drew Thomas to the city, as they did many young soldiers in South Korea. And it was in Seoul that he would meet someone who would change his life forever.

In fact, Thomas encountered a woman by the name of Pae Seong-Kuem at the Non-Commissioned Officer’s Club. Sparks immediately flew, too, despite Kuem being five years his senior, and they struck up a relationship. As mentioned, Kuem, whom Thomas affectionately called “Connie,” had a son from a previous relationship, but it wasn’t long before she was pregnant again, this time by Thomas.

Happily, while the Summer of Love was sweeping across America, Thomas and Connie were staging their own love-in in Korea. And it was only sweetened by the arrival of James and Sandra in September 1967. So when Thomas’ tour came to an end in 1969, the stage seemed set for the newlyweds and their children to begin their life together in the U.S.

But, as it turned out, things weren’t that simple. In fact, while James and Sandra – having been fathered by an American citizen – were permitted to emigrate to the U.S., Connie and her son were denied access. Hence, Connie refused to allow Thomas to take any of the kids with him to America without her.

So, alone in America, Thomas would write to Connie for news of the kids. However, it seems that the massive distance between them began to affect their relationship. Indeed, so desperate was Thomas for closer contact with his family that he actually volunteered to fight in Vietnam, and in 1971 he managed to visit South Korea on a month’s leave of absence.

Things weren’t the same, however. In fact, that 1971 visit was the last time Thomas would ever see the family together. That’s because after he left South Korea his relationship with Connie continued to deteriorate. Indeed, Thomas’ last correspondence with Connie was a letter sent in 1974 in which Connie asked Thomas to return and take James and Sandra to America with him.

But for Thomas this was an impossibility, as he had recently filed for bankruptcy. And things got worse from there, because the letters he sent to Korea started to be returned without any indication as to where Connie had moved. Consequently, with no obvious means to maintain the relationship with his twins, Thomas set up a new life with a woman from his hometown.

Her name was Polly Paquin, and, like Connie, she already had children from a previous relationship. So it was that Thomas divorced Connie in her absence and married Paquin – as well as adopting her children, Scott and Charlene. Thomas eventually had a son by Paquin, too, though the twins were never far from the veteran’s mind.

Then Thomas caught a break in the early 1980s. It seems that he had been working to discover the whereabouts of Sandra and James and finally discovered that Connie had given them up for adoption. Indeed, with the help of the U.S. State Department, among others, Thomas learned that they were now being cared for in America. However, owing to privacy laws, he wouldn’t be given any more information.

All Thomas knew was that the twins had been taken to America in 1976, meaning that they were either eight or nine when they were adopted. No doubt this came as a huge blow to Thomas, whose attempts to find his children were increasingly hitting dead ends. “I’m mad. I was highly upset,” Thomas explained to ABC News.

Fortunately, though, that wasn’t the end of the story. In fact, it was the advent of social media that made Thomas discover a fresh opportunity to broadcast his search to the world. So in April 2015 he created a Facebook status pleading for help in his search for Sandra and James. The post was accompanied by images of the twins along with their birth certificates and adoption documentation.

“I have been searching for decades, unsuccessfully; but have decided that perhaps Facebook could help me to find them,” wrote Thomas. And, though his tone was reserved, the longing and emotion shone through in his message. Moreover, the post was about to provide the breakthrough he so desperately desired.

Thomas’ story was picked up by someone at ABC, who subsequently put investigative genealogist Pam Slaton on the case. With the help of ABC News’ Seoul Bureau Chief Joohee Cho, Slaton set about unpicking the mystery of the Thomas twins. However, it wouldn’t be easy.

This was because the twins’ birth dates, coupled with the fact that they were adopted together, was just not enough information to track them down. “That’s when the panic started setting in,” Slaton told ABC News’ 20/20. Yet, out of the blue, help finally came from South Korea.

Indeed, Thomas was contacted on Facebook by one Keonsu Lee, a Seoul-based police detective with a specialism in finding missing children. Lee was consequently put in contact with Cho, and with his help she was able to track down the son whom Thomas had adopted when he married Connie all those years ago.

His name was Jae-Im, and despite initial reservations, he agreed to release James and Sandra’s adoption records from the Korean adoption agency where they were stored. Additionally, Jae-Im and his wife were able to shed a little light on Connie’s behavior after her marriage to Thomas had begun to break down.

Apparently, Connie believed that Thomas had met another woman while he was in Vietnam. And her decision to put the twins up for adoption might actually have been well-intentioned, since, according to Jae-Im’s wife, “it meant huge success at the time to be going to America, equivalent to paradise.” Meanwhile, Slaton finally had access to the twins’ adoption records and was able to track the pair down in the U.S.

Image: Susan Williams via ABC News Susan and Timothy are pictured left — Image: Susan Williams via ABC News *Susan and Timothy are pictured left.*

Slaton eventually discovered that both twins had been adopted by an academic in Pennsylvania. What’s more, James was now going by the name Timothy James Parker and worked as a trucker in Missouri. Sandra, meanwhile, was now named Susan Williams and was living in Wisconsin with her husband and two kids.

Image: YouTube/ABC News via JustForMedia

And so, after arranging initial phone calls between Thomas and the twins, Slaton and the 20/20 show brought the family members back together for an emotional reunion in New York. On that day, after almost 50 years of not knowing who their biological father was, Parker and Williams were overwhelmed with emotion. Indeed, Parker said, “I just can’t believe you’re my actual father. I’m standing right here looking at you.” For Thomas, meanwhile, a decades-old wound was finally healed. “I’ve been looking for a long time,” he said.