Tom, I don't know if talent and/or intelligence skips generations; however, I have observed, on many occasions, that some children of very successful private business owners fail to "make the grade" in carrying-on their parent's business or otherwise fail to exhibit the skills that lead to their parent's success. In some cases, the parent recognizes this and sells the business rather than "pass" the business to children and in others, the kids run the business into the ground.
Rather than talent and/or IQ, I've attributed these situations to a lack of motivation and/or interest in the parent's business; a mistaken assumption that the family name was somehow "magic" and the heirs were either "sheltered" from or ignored their parent's early struggles to establish the business.
If I had to choose, my observations of the "offspring" who didn't "make it" would place more emphasis on nurture rather than nature.
I think the same would be true in the world of golf architecture with one possible exception...
GCA is an artform. There have been times wherein I have wondered if an "offspring's" apparent success has more to do with the family name rather than the actual work product. Certainly, not all, but some.
Is it possible that some clubs become enamored that the "famous X" (or son of famous X) is doing the work and are reluctant to question the plans drawn because, afterall, the "famous X" is the expert?
Everyone on this board has a preference, but even with our preferred architects, some of their work products are better than others.
A lot can be said for the power of a name. Does the power of that name distort our view of their end product?