Girls take more selfies then boys because girls like to share pictures of themselves then men on the internet. Girls tend to prefer head shots, while men are more likely to select a full body image. Girls are more likely to select pictures of themselves to give others the impression they are attractive, they are beautiful.
And the most important reason for girls selfie taking is combination of ego-stroking along with societal pressures that places a higher importance on female physical attractiveness and desires to live up to perceived social norms.
Many of the girls try to take selfies to use effects on there faces to look differently. Many of the selfie taking apps are only for girls because girls love to use them. Girls use effects and compare with the others. Just like they have competition between them who will take more selfies.