The person may mention siblings ​ — even twins. If he does, we could point out how natural that comparison seems to be.
فَٱللهُ أَشَارَ إِلَى يَسُوعَ أَنَّهُ ٱبْنُهُ ،‏ وَيَسُوعُ قَالَ إِنَّ ٱللهَ هُوَ أَبُوهُ .‏