  Stellar members of binary systems are formed from the same material,
therefore they should be chemically identical. However, recent high-precision
studies have unveiled chemical differences between the two members of binary
pairs composed by Sun-like stars. The very existence of these chemically
inhomogeneous binaries represents one of the most contradictory examples in
stellar astrophysics and source of tension between theory and observations. It
is still unclear whether the abundance variations are the result of chemical
inhomogeneities in the protostellar gas clouds or instead if they are due to
planet engulfment events occurred after the stellar formation. While the former
scenario would undermine the belief that the chemical makeup of a star provides
the fossil information of the environment where it formed, a key assumption
made by several studies of our Galaxy, the second scenario would shed light on
the possible evolutionary paths of planetary systems. Here, we perform a
statistical study on 107 binary systems composed by Sun-like stars to provide -
for the first time - unambiguous evidence in favour of the planet engulfment
scenario. We also establish that planet engulfment events occur in stars
similar to our own Sun with a probability ranging between 20 and 35$\%$. This
implies that a significant fraction of planetary systems undergo very dynamical
evolutionary paths that can critically modify their architectures, unlike our
Solar System which has preserved its planets on nearly circular orbits. This
study also opens to the possibility of using chemical abundances of stars to
identify which ones are the most likely to host analogues of the calm Solar
System.
