KEN Allen loves families — and a decision he made decades ago to help couples who couldn’t conceive has now changed his life forever.

The retired South Australian school principal had married his wife Sue back in 1982. Together, they had their daughter Leah, before having their first son Marcus five years later.

But before they had their third child Jason, and then adopted another daughter from Taiwan, Ken asked Sue a question.

He asked her if he should become a sperm donor.

“I really recognised the need for sperm donors, um, and came home to Sue and said, ‘Look, we’ve got these beautiful kids, you know, and there’s so many couples that are there that my heart bleeds for,’” he recalled.

Sue didn’t hold him back.

“I was working at the same hospital, so I had a lot of interaction with these sorts of families as well, so … there was no hesitation at the time,” she said.

Ken then went to a sperm donor clinic in Melbourne over a period of two months. He made anonymous donations he hoped would bring new life to young couples trying to conceive.

He wasn’t able to contact any children who were conceived using his sperm, nor did he expect to.

But he did leave a secret message on his two-page donation form that had brief details on his eye colour, hair colour and height.

“Man cannot discover oceans unless he has the courage to lose sight of the shore,” he wrote.

“I knew that there was a possibility that one day an offspring may in future get a hold of this, and I really wanted to encourage them to pursue their dreams and also to perhaps pursue me,” he said.

“If you can, come find me.”

Then while on a lunch break at work in 2014, Ken got a call from the IVF clinic where he’d donated sperm years ago.

He discovered he was a father to 11 kids living across Australia.

Ken recalled how a woman rang telling him: “Well, you have, um, 11 donor children, and two of them are girls, and nine of them are boys.”

And she said: “How does that make you feel?”

Ken then recalled saying: “Well, um, I’m not a drinking man, but I … could do with something right now.”

“Eleven, eleven, eleven, you’ve got to be kidding me,” he said.

Now 59, Ken has met four of his children conceived with his donated sperm.

The first one he met was Chloe Allworthy, 25, who spent seven years searching for her biological father.

She even went to YouTube to tell her story as she searched for him.

Finally, she got a phone call from Melbourne IVF, who had had contact from Ken.

She then flew to Adelaide and met him.

“That flight was so anxiety-provoking. I was just thinking the whole time, ‘I’m about to meet this man that I’ve dreamt about, you know, and he’s at the airport and I’m gonna see him, and I’m gonna hug him for the first time,’” she told Sunday Night.

“It’s so hard to describe it. It was just like an overwhelming feeling of compassion, of love, of, um … and just warmth, really,” Ken said.

Chloe then started searching for of her siblings. She first found Robert Gyamathy, whose parents had also used Ken as a donor. This meant Robert was Chloe’s half-brother.

When she got Robert to finally meet Ken, he said: “Physically, I could see the similarities between us immediately. I was a little bit shell-shocked just for a moment just to know this … this is my biological father. This is a big moment for me in my life. It was incredible, and he was … just gave me a big hug and, yeah, he didn’t let me go for about a minute, but it was excellent.”

Melissa Millar then later found out that Ken was also her biological father after her “dad” Wayne died of a heart attack. She had never been told she was conceived with donor sperm until Ken made contact.

“At that point, I just cried. I didn’t know how to feel. I was just, …. like, numb inside,” she said.

“The thing, though, back in my mind was that, ‘Am I disrespecting my dad?’”

“That was one big thing, like, cause my dad didn’t want me to know. I just feel horrible that he’s not here and I can’t talk to him, … because he was, like, a big part of my life.”

Nathan Coff, 25, is Ken’s fourth child who has now made contact with him, after first getting to know Chloe.

But there are still seven sons out there that Ken wants to meet.

He told Sunday Night he wants to tell them about his current medical issues, which include being diagnosed with symptoms of Parkinson’s disease over the last four years.

“I don’t want them, you know, feel as though they’re being forced, but I’d really love to make some form of contact so they know who I am. And … And I also, um, … would like to let them know about my health as well and where that sits,” he said.

“There are a number of other medical issues that have a strong hereditary basis, and they’re starting to show up in some of our children now, so … they need to be aware of those medical issues so that they can actually take good care of themselves and seek the appropriate treatment.”

Chloe, Robert, Melissa and Nathan agree with Ken that there’s room for seven more — if anyone comes forward.

“It’s good to know, you know, I have these people. Like, it’s overwhelming. As Ken said, it’s just a big thing,” Melissa added.