According to the connections in the tree Wilhelmina Catherina Francina Basson is the niece of Martha Helena Basson. Martha being the mother of Willem George Geere (1802) and Wilhelmina being the wife of the same Willem George Geere. Seems way too close for this marriage to have been kosher.
Thoughts?
Yes, WCF Geere (Basson) and her cousin Willem George Geere were married. See https://www.geni.com/family-tree/index/6000000022166375256#60000000...
Not advisable, but certainly not disallowed or uncommon (in South Africa) at all. I can site many such examples.
Regards,
Johann