Boys can be a lot more colorful than girls.

Chameleons do not and cannot change color to match any hue in their environment. Instead, their shifts in color occur subconsciously, based on temperature, light, and mood, and they occur only within the natural color range of the particular kind of chameleon. Among panther chameleons, the females tend toward earth tones, while males exhibit a variety of jewel tones.

Of course, some girls and boys don’t look any different from one another.