Generally, humans can breed with other races seen in the One Piece world, like merfolk, fishmen, longlegs, three eyed, longarms, and snakenecks, with the offspring inheriting its non human parent features (merfolk's tail, fishmen's appearance, longleg's legs, etc.) Some traits are retained even after continuous breeding with normal humans, such as Chimney's swimming abilities though she is one quarter mermaid. The apparent weakness of the humans in the One Piece world often makes other races, such as the fishmen, think poorly of them.
This can result in heavy amounts of racism towards humans, although not all fishmen share this belief.
One such example is Charlotte Linlin, who stood three times the height of her normal-sized parents at just five years old.
This also works the other way around, as many of Linlin's own children (such as Charlotte Pudding) only grew to average size as adults.
Almost a constant look in the eye, not too intimidating as if a stare, but consistent.
But she also is very inclusive to people around her.
Some humans have an ape-like appearance such as Masira, Shoujou, the Utan Divers, Hamburg and the Coffee Monkeys; Masira claimed openly to be human and not ape, although he was not insulted when called a "monkey".