the "3rd generation curse" is more likely to be related to the larger number of family members taking income from the business than it is competency of those 3rd generation family members active in the business.
Yes i can see this coming too, i started my Business from zero, my Son is playing a big part in the business now at 29, but wants to cut out his 2 younger simblings 25 & 16, he has benefited greatly now living in a very luxurios property and 2 very nice new cars on the Drive, but he wants to live the millionaires life style 'now' with the Company profits, its causing friction as i want to reinvest and start an additional side line in Manufacturing.