Kate Hudson affectionately calls Kurt Russell 'pa' and was raised by the Hollywood actor from a young age.And on Wednesday, the Music star paid a heartfelt tribute to Kurt as he celebrated a milestone birthday.MORE: Kate Hudson showcases toned physique in tiny crop topTaking to Instagram, the mother-of-three shared a sweet throwback photo of herself as a little girl alongside her siblings Oliver Hudson and Wyatt Russell, Kurt's son Boston and her mother Goldie Hawn.MORE: Goldie Hawn's family's