Boomers vs. Gen X: Who’s the Wealthiest of Them All?

This tweet has been making the rounds:

Fraction of all US wealth owned by Boomers & Gen-Xers when the average member of each was age 35:
Boomers, 1989 21%GenX, 2008 8%
The average Millennial turns 35 in 2023. Right now they own 3%.
There will surely be political implications.
— Kurt Andersen (@KBAndersen) November 24, 2019

One of my readers emailed this to me and asked if it was for real. I promised to look into it.
The short answer is yes, it’s true. It’s based on the Fed’s Survey of Consumer Finances, which is a pretty reliable set of data, and the numbers are accurate. Boomers at age 35 held a much larger share of national wealth than Gen Xers did when they turned 35 a decade ago.
So what’s going on? Is there really such a huge gap? I think probably not, and it has to do with the huge increase in income inequality over the past few decades. Compared to 1989, a much larger share of national wealth is tied up in the wealth of the very rich these days, and Gen X isn’t yet old enough to have a big share of that. It’s mostly boomers—either by inheritance or by simple accumulation—who control that wealth. If you look at median wealth instead, the difference between boomers and Xers would be much smaller.
That’s my guess, anyway, but I can’t find the data to support it. It’s probably out there somewhere, though. Can anyone help us out here?