I believe that you are thinking of some or all of the books in "The Galactic Milieu Series" by Julian May. (If you click on that title, it will take you to the Wikipedia page about the series.)
It has been many years since I read any of the books in question, but they spend a lot of time examining the various members of the Remillard family during the 20th and 21st Centuries. Members of this family usually have genes that tend to make them highly gifted in various psychic feats, with -- as you said -- some members steadily moving up the ladder to positions of greater and greater authority within their civilization. One problem here is that some family members are not nice people, and one of their most powerful members becomes the main ringleader in a very messy revolution called "the Metapsychic Rebellion." Entire planets are depopulated before that rebellion is finally crushed.
Online resources remind me of something I'd forgotten -- Rogi Remillard, narrator of at least part of the series, grows up in Berlin, New Hampshire, which continues to be "home turf" for much of the clan as one generation follows another. That "Berlin" may be the one you were remembering. I can't recall if that Berlin (or the one in Germany, for that matter) gets "nuked" or otherwise devastated by the end of the Metapsychic Rebellion, but it is possible that something along those lines did happen.
Rogi frequently has conversations with what appears to be a very powerful disembodied entity with friendly intentions, which he sometimes calls "the Family Ghost," or "the Ghost" for short. Occasionally, in time of great need, the Ghost seems to have exerted its own metapsychic strength to assist Rogi in overcoming a deadly crisis.
In addition -- regarding your mention of a "galactic consciousness" which has an overall plan -- the term "Unity" is frequently used in the text to describe a process by which the human race in general could become integrated into something called "the Galactic Mind," of which several other starfaring species with metapsychic capabilities are already members in good standing. I believe the aforementioned Metapsychic Rebellion was a result of extreme skepticism on the part of many human beings regarding whether this "Unity" would really turn out to be as marvelous an idea for our species as the aliens claimed it was bound to be. (After all, what's "good" for someone from another solar system, with a whole different metabolism and so forth, might not be equally "good" for you and me.)
There appears to be some confusion about just how many books count as part of "The Galactic Milieu" series.
A novel called Intervention (1987) sets the stage by beginning in the 20th Century and working forward some decades, with Rogatien "Rogi" Remillard as the narrator. He and his twin brother, Donatien "Don" Remillard, grow up realizing they both are powerfully gifted with what Julian May called "metapsychic" abilities. They generally prefer to keep this secret for as long as possible.
Then come the three books which May regarded as "The Galactic Milieu Trilogy," as it says on their covers (I just checked Amazon), which mostly focus on younger members of the Remillard family in the 21st Century, as I recall -- after metapsychic powers have been officially recognized by Earth's governments, and contact has been made with powerful aliens who want to help us properly develop our potential as we become integrated into a larger civilization (the Galactic Milieu, of course!). Those three novels are Jack the Bodiless (1991), Diamond Mask (1994), and Magnificat (1996). I read all four, in order, long ago.
Please note that the Wikipedia entries on "Julian May" and "Galactic Milieu Series" basically take the position that the introductory novel Intervention counts as #1 in the series. On the other hand, Wikipedia also admits that Julian May claimed to view it differently, seeing Intervention as a mere "link-tale" that helps connect things together (including a previous popular series she'd written, called "The Saga of Pliocene Exile," which is set in the same fictional universe, although most of it happens six million years ago!). And I see that the ISFDB entries for "Julian May" and "Galactic Milieu" tend to follow the author's lead by listing Jack the Bodiless as #1 in the "Galactic Milieu" series (or trilogy, whichever you prefer to call it).
So here's my best advice: If you (or anyone else reading this) choose to invest the time to read or reread this material from scratch, then, to get the full impact, you should do what I did, and read all four volumes in order, so that you can clearly understand the sequence of events as Remillard family members (and friends and in-laws and so forth) get older, and reproduce, and sometimes fight each other to the death. But think of the sequence as going this way:
The Galactic Milieu
- Intervention: A Root Tale to the Galactic Milieu and a Vinculum between it and The Saga of Pliocene Exile (that's apparently the full title and subtitle -- I was just calling it "Intervention" above)
- Jack the Bodiless
- Diamond Mask
I tried to have Intervention be "Number Zero," reflecting its status as an important introduction or prelude to the main trilogy, but the site software kept automatically "correcting" the zero to replace it with a "1" in front of the first item in a numbered list. So I settled for this approach instead, giving that book a bullet point but not a numeral.