I know one billionaire family who have managed to instil a sense of proportion, industry and obligation into the various younger members: there are no private jets, chauffeurs or suchlike.
Land Rover has recently turned a corner (it made a profit of about $1.5 billion last year), but Jaguar cost Ford some $10 billion during its 18-year stewardship and its sales were in decline.
Their allele frequencies at numerous genetic loci gradually become more and more different as new alleles independently arise by mutation in each population.