Justin Bieber, 27, showed off his sweet instincts when she helped take care of his baby niece Iris on Aug. 22. The singer shared a post that included several new pics of him holding the baby girl, who is the daughter of his wife Hailey Baldwin‘s sister Alaia Baldwin, 28, and her husband Andrew Aronow, while hanging out outside. He was wearing a short-sleeved tan button-down patterned top over a white tank top, black pants, and green, white, and gray sneakers during the bonding time.