story identification - 1980s sci-fi book club trilogy about a rich, space-faring multi-generational family

I'm looking for the title of 1980s sci-fi book club trilogy about a multi-generational family. The covers had faces on them and the matriarch had a white streak in her hair. Rich family, space-faring and it had family trees in it. I got it from the Science Fiction Book Club some time in the 80s.