Below is a selection of British siblings with Rowan, from the last century to modern times. All uses of Rowan are masculine (as requested) unless indicated by (g). The year relates to the decade of birth for that set. Brackets around the first name indicates that the person was called...
I like how many of the families from the late 19th and early 20th century would fit right in today - like William, Edith & Rowan; Archibald, Rowan & Hazel; or Leonore, Rowan, Violet & Basil.