User blog comment:Miskos3/Fairy Tail 525: Why Did the Emperor Never Love His Child?, Review/@comment-2214433-20170305095443/@comment-7418318-20170305181404

And it makes sense that Silver and Gray smelling the same was something out of the ordinary, if not outright unique.

If all parents and children smelled similar or even the same, it would have been a natural reaction for the Dragon Slayers to assume that Silver was Gray's father, but none of them drew the conclusion of a relationship from the similar scent. They were just baffled about something like that happening.