  Stellar chemical compositions can be altered by ingestion of planetary
material and/or planet formation which removes refractory material from the
proto-stellar disc. These "planet signatures" appear as correlations between
elemental abundance differences and the dust condensation temperature.
Detecting these planet signatures, however, is challenging due to unknown
occurrence rates, small amplitudes, and heterogeneous star samples with large
differences in stellar ages, and therefore stars born together (i.e., co-natal)
with identical compositions can facilitate such detections. While previous
spectroscopic studies were limited to small number of binary stars, the Gaia
satellite provides new opportunities for detecting stellar chemical signatures
of planets among co-moving pairs of stars confirmed to be co-natal. Here we
report high-precision chemical abundances for a homogeneous sample of 91
co-natal pairs of stars with a well-defined selection function and identify at
least seven new instances of planetary ingestion, corresponding to an
occurrence rate of 8%. An independent Bayesian indicator is deployed, which can
effectively disentangle the planet signatures from other factors, such as
random abundance variation and atomic diffusion. Our study provides new
evidence of planet signatures and facilitates a deeper understanding of the
star-planet-chemistry connection by providing new observational constraints on
the mechanisms of planet engulfment, formation and evolution.
