Sad to say, the seeds for the present epoch of Climate change were clearly laid long before Bobbisox's generation, let alone during it. This in no sense means that Bobbi or any other person is individually responsible. There is a collective responsibility, a failure of past generations, in consistently putting environmental concerns well behind economic growth. All of that took place well before the modern period, and certainly well before the most recent generation grew up.
Nor is it any answer to call Thunberg brainwashed. At its core, her point is simply this: listen to the overwhelming consensus of scientists, as voiced in the IPCC reports and countless thousands of papers from tens of thousands of specialist scientists, whose expertise it is to both study and to solve these problems. If the best you can come up with is to blame the youngsters for both causing the problem (as Bobbisox appears to), and in even thinking there is a problem at all (as is implicit in the brainwashing accusation), then you need to come up with better responses. And the only response is to take responsibility.