Beyoncé is one of the world's most famous singers but to her the most important thing in her life is family.MORE: Beyoncé's fans in disbelief over star's rare appearance with her childrenAnd on Saturday, the Lemonade hitmaker marked her husband Jay-Z's 52nd birthday with her children, Blue Ivy, Rumi and Sir.The family are notoriously private when it comes to their personal life but no doubt made sure the rapper had a day to remember.VIDEO: Beyoncé's daughters Blue Ivy and Rumi steal the show