Mum and Dad, will not be affected massively I expect except various stock portfolios to be hit somewhat as expected.
Myself. PHD was finished recently, got a lot of funding from the EU for research as part of it. However do have plenty of other friends and colleagues still doing there's and some faculties do get a lot of research money from the EU so they will be affected pretty heavily I expect. No way the government will have enough to step in after all this. For job, I think its tentative, consultancy role to Civil Service, so if they make cuts then well that would suck.
Brother works for investment banking division of a German Bank. See how it pans out, but he would not be surprised to see his role move to Frankfurt.