Yet as Wayde Van Niekerk runs the 400 metres heats at the World Athletics Championships in London on Saturday, eyeing more athletics landmarks, he would not want anyone but this "amazing woman" to be guiding him.
Botha has three children, five grandchildren and five great-grandchildren. "Oh yes, I'm a great-grandmother -- but not of Wayde!" she laughs, when asked how they gel with their 50-year age gap.
South African Van Niekerk says he teases his Namibian mentor for her stubborn ways and Botha gives him old-fashioned looks about his blaring music. "She's strict," smiles Van Niekerk, yet, clearly, their relationship comes with deep affection, trust and respect.
It has worked famously in the five years since Van Niekerk enrolled at the University of the Free State in Bloemfontein and asked to join the training group of Botha, their athletics coach of 25 years.
Under her tutelage, not only has he become a world record breaker and Olympic champion at 400 metres, clocking 43.03 seconds in Rio last year, but also the only man ever to break 10 seconds for 100m, 20secs for 200m and 44secs for 400m.
In London, he could become the first man since Michael Johnson in 1995 to achieve the 200m/400m double at the world championships.
Botha smiles that, actually, like the rest of her training group, she cannot help but see Van Niekerk like one of her "children". From schoolchildren to veterans, they all call her 'Tannie Ans' -- Auntie Ans in Afrikaans.
"There are 32 of them and I treat them the same. They're an exceptional group of children," she said in an interview with Reuters.
"Wayde really loves to be in the group because they're like a family. When he has to train on his own, he always complains 'Tannie, I'm alone, I want my friends, my other athletes here with me.'"
Van Niekerk's dramatic rise over the past year has proved a real culture shock for Botha, finding herself at the centre of a media fuss.
After a fifty-year self-taught coaching career which began back in Namibia when she couldn't find a coach for her daughter Herma, Botha, once a long jumper and sprinter herself, said: "In a way, it's a really difficult experience for me at 75.
"In another way, I'm still the same person, still a great grandmother who loves gardening and all my other activities. So it's not made any difference to me as a human being.
"It is physically demanding at my age but I enjoy it. I'm walking a lot and then stretching. I've found when you have the enthusiasm and the love and passion for something, it's no big issue.
"I'm just so blessed and am so grateful to do the things I love at my time of life."
Van Niekerk feels blessed to have her guiding him too.
"She's an amazing woman," he told reporters on Wednesday. "I don't think she's as scary as some people think but she is a tough lady.
"She's fixed in a lot of her ways but if you approach her with love and respect, then you can win her heart quite easily.
"Once you step on the wrong side then you can find it's quite difficult to win her over. I haven't stepped over that mark, but I do like to tease her which she is not used to."
The ageless Botha loves guiding Van Niekerk, but what does she prefer -- being the perfect coach or the perfect great grandma?
"I think it's both. When I have the opportunity to be with my family, I try to make it really, really quality time," she smiled, before adding with a glint in her eyes: "Yet when I'm busy coaching, I have a one-track mind."
(Reporting by Ian Chadband; Editing by Toby Davis)
