Aged 15 Nneka was introduced to the triple jump and quickly found her niche qualifying two years later to compete for New Zealand at the 2005 IAAF World Youth Championships in Morocco.
However, while Nneka's profile in the sport started to rise, Ebuka's interest started to wane.
"I don't know why it was but as soon as I hit puberty I lost all my speed," he explains. "I remember competing in the Auckland Junior Championships and for the first time I didn't win a medal. I was training hard but not improving and that's when I moved into soccer."
Ebuka quit club athletics and stopped training, although he continued to compete in track and field for Saint Kentigern College, where he showed a natural flair for the triple jump.
Post-school the youngest of the three Okpala siblings (they also have a middle brother, Ify) walked away altogether from athletics to focus on football, where he played as a striker and was good enough to earn a trial for ASB Premiership outfit Auckland City
Yet Melbourne-based Nneka - a five-time national New Zealand women's triple jump champion - refused to let Ebuka's rich athletics potential go to waste.
"She definitely kept pushing me to get back involved in athletics and kept on at me," explains Ebuka.
"He was really good at athletics and I felt he was giving away his talent too early," she says. "If he put some effort in I knew he could get back to where he was. We had so many conversations, but he is so stubborn. He doesn't want to do anything he doesn't want to do."
However, Nneka's persistence finally paid dividends when she persuaded her kid brother to come to see her in Melbourne in June 2014. She took him to the track one day and her coach, the Belarussian Vasily Grischenkov, proved the catalyst for his reintroduction to the sport.
"He (Grischenkov) described him as a 'wasted talent' after just taking one look at his physical stature," says Nneka.
With the comments ringing in his ears in November that year he returned to Melbourne to train with Nneka and her squad for two weeks. He impressed with his natural co-ordination and ability to learn quickly. After four years away from the sport he was hooked once more.
Following just a few months training Ebuka finished third behind Philip Wyatt at the 2015 New Zealand Track & Field Championships with a leap of 14.86m before he started working with coach Paul Lothian - coincidentally the former coach of Nneka.
Ebuka, who competes for Pakuranga AC, admits several hamstring pulls put the brakes on his winter preparations and he struggled to find his rhythm in the early part of the season. In fact, such was his lack of confidence he has severe doubts he could jump beyond 15m leading into the New Zealand Track & Field Championships earlier this month.
However, something must have clicked at the Caledonian Ground in Dunedin as Ebuka wrestled the lead from Scott Thomson from Wellington in round four with a leap of 15.48m before he then bounded out to a mighty - albeit wind-aided - effort of 15.85m in the final round.
So why does he feel the day went so well?
"I think it is because Nneka jumped a New Zealand record the day before," says Ebuka, who also won bronze in the long jump with 7.04m. "I was thinking about (her record) that morning and even though my first couple of jumps were bad I knew if I had one good jump, I could build on it."
While Ebuka's return to the sport after a lengthy absence has started with a bang his 27-year-old big sister's career also continues to progress. Disappointed to miss out on a place in the team for the 2014 Commonwealth Games in Glasgow last year she twice bettered her national record with leaps of 13.62m and 13.65m.
Yet perhaps the most encouraging element to her 2015 was a respectable eighth place finish at the World University Games in Korea.
"It was my first international experience for ten years (since the 2005 World Youth Championships) and I felt I performed pretty well," she explains.
Coming out of the World University Games in good condition she believes a combination of working on her speed and step phase has contributed to her good form this year - a point best demonstrated at the Melbourne Track Challenge where she bounded out to the two longest jumps of her career with 13.89m leap in round one followed up by a 13.80m effort in round two.
"The atmosphere was amazing," she says of the competition in her adopted home city. "I was really firing and pumped. I really wanted a big jump in the competition."
Just 21 centimetres shy of the Rio Olympic B standard of 14.10m she hopes to achieve the mark at the Australian National Championships in Sydney (Mar 31-Apr 3) and may consider travelling to North America or Europe in pursuit of her Olympic ambitions later this year.
"I am confident there is more to come," she explains. "I just need to replicate what I did in Melbourne, add a little more distance with each phase of my jump and go at it with more gusto."
While Nneka continues to chase her Olympic dreams, Ebuka's season has now drawn to a conclusion. However, with his rising status in the sport he has not discounted matching her big sister as a national record holder (note, the men's national triple jump mark of 16.22m was set 38 years ago by Phil Wood) and further down the track lining up alongside her in the Black Singlet.
"When I went over to Melbourne in November 2014 we both said it would be cool if we both made the New Zealand team for the 2018 Commonwealth Games," says Ebuka, 23. "With another two more years under my belt by then, I think I could make it."
The pair regularly converse on the phone to talk triple jump, although as Ebuka says of her elder sister's advice it can be both helping and an "annoyance."
"I will be asking her something on step technique and she will be throwing some barbs in there about am I eating right or I can't run properly," he says with a smile of his sister's verbal approach.
But is Ebuka happy that Nneka persuaded him to return to the sport?
"I guess Nneka must have seen something in me that I didn't see myself," admits the ASB payments officer. "Flying down to Dunedin for nationals I thought it is great I am finally doing what I thought I would be doing when I was young and good."
