It has been suggested that {beta}Picb has a supersolar metallicity and subsolar C/O ratio. Assuming solar carbon and oxygen abundances for the star {beta}Pic and therefore the planet's parent protoplanetary disk, {beta}Picb's C/O ratio suggests that it formed via core accretion between its parent protoplanetary disk's H2O and CO2 ice lines. However, {beta}Picb's high metallicity is difficult to reconcile with its mass Mp=11.7MJup. Massive stars can present peculiar photospheric abundances that are unlikely to record the abundances of their former protoplanetary disks. This issue can be overcome for early-type stars in moving groups by inferring the elemental abundances of the FGK-stars in the same moving group that formed in the same molecular cloud and presumably share the same composition. We infer the photospheric abundances of the F-dwarf HD181327, a {beta}Pic moving group member that is the best available proxy for the composition of {beta}Picb's parent protoplanetary disk. In parallel, we infer updated atmospheric abundances for {beta}Picb. As expected for a planet of its mass formed via core-accretion beyond its parent protoplanetary disk's H2O ice line, we find that {beta}Picb's atmosphere is consistent with stellar metallicity and confirm that it has superstellar carbon and oxygen abundances with a substellar C/O ratio. We propose that the elemental abundances of FGK dwarfs in moving groups can be used as proxies for the otherwise difficult-to-infer elemental abundances of early-type and late-type members of the same moving groups.