Not to defend Loz but Cairo is likely blonde because of Kyle and Lauryn equally because the gene for blonde hair is recessive not dominant. Kyle’s mum is a blonde, it is almost guaranteed that she gave him that recessive gene meaning that while Kyle isn’t blonde, he has the ability to in the right circumstances have blonde children. Hence, mixing with another blonde recessive gene from Annie’s side or Lauryn’s side would create a blonde child. Without Kyle having a blonde gene in his gene pool, it is unlikely that without a mutation, any of his children could be blonde.