Sven,
Agree on the tree. Very few architects start and stay with one firm, or apprentice at one firm and then start their own firms, like I did. And after a few generations, it really gets confusing. I have had apprentices who either before or after they left my firm work with more than one architect, including Nicklaus, Rees or RTJII, Von Hagge, and who knows who else.
Do they fall under the RB Harris/Killian and Nugent/Brauer tree, or somewhere else? It is quite possible they worked for me the longest, but had more substantial projects with those other firms. Actually, most ended up still in the biz and working for those others longer, but first worked for me. So, what would be the criteria for their family tree roots? I guess its up to them, or we find a different system.
As to tendencies, most architects will admit to copying someone, an idea, or even their own green designs in new projects. I mean, if you like it, and it seemed to work, why not? As I have said before, if a Redan is a good hole in Texas, it should be good in China, etc. Most architects, like CBM, did write about the make up of the ideal course, in the theoretical world, and tried to get as close as possible to that in the reality of specific sites.
Sometimes, I have taken a green I liked, and substituted one bunker where three had existed before, or grass for sand, or something else, and also counted on different shapers, the surrounding topo and fitting it to trees, etc. to make it different enough. That is raising the question of just how much change from green to green does it take to be counted as an original design?
Seems to me that in music there is some sort of minimum notes that need to change to avoid plagiarism charges, but its quite low. I haven't heard of any architects plagiarism cases (even Tour 18 was ruled to overstep its bounds by including the iconic Harbor Town lighthouse in its versions) but it is still an interesting theoretical question to ponder over a few post round beers among architects.