  GW190521 was the most massive black hole merger discovered by LIGO/Virgo so
far, with masses in tension with stellar evolution models. A possible
explanation of such heavy black holes is that they themselves are the remnants
of previous mergers of lighter black holes. Here we estimate the masses of the
ancestral black holes of GW190521, assuming it is the end product of previous
mergers. We find that the heaviest parental black holes has a mass of
$62^{+21}_{-19}$ M$_\odot$ (90% credible level). We find 78% probability that
it is in the $50$ M$_\odot-120$ M$_\odot$ mass gap, indicating that it may also
be the end product of a previous merger. We therefore also compute the expected
mass distributions of the "grandparent" black holes of GW190521, assuming they
existed. Ancestral black hole masses could represent an additional puzzle piece
in identifying the origin of LIGO/Virgo/KAGRA's heaviest black holes.
