Gerald Boyd writes:
"I was thinking about 'six degrees of separation' ....... my muse whispered, “Why not a relationship between Petite Sirah and Pinotage?” On the surface the idea sounded implausible, but these two seemingly different grapes do share some things, and maybe at one of those six levels Petite Sirah and Pinotage are related"
It looks to me as if the article is incomplete but the meat of the historical links are there.
Talking of Petite Sirah: it is a variety I greatly enjoy and have long thought would be ideal for the Capes sunny climate. Fairview released South Africa's first varietal Petite Sirah which I have drunk twice and it confirmed I was right; it was an excellent wine.
And there is a real connection between Pinotage and Petite Sirah. A parent of Petite Sirah is Syrah, and a parent of Pinotage is Pinot Noir. Pinot is an ancester of Syrah, thus Pinotage and Petite Sirah are related.