These three people were not photographed together. The boy is plunked on top of the older girl. Look at the sharpness of the right margin of the boy. Also, not one strand of hair from the older girl is over the boy's shoulder. The lighting is a dead give away. Look at the young girl; she's illuminated by light coming from the left. The other two people are lit from the right. If they were photographed together, they should be lit in the same manner.

The boy's head came from a different body. The skin tone of the face and hand are quite different. The boy's skin color also abruptly changes at the bottom of his neck.

Both of the older girl's eyes are black holes. They aren't reflecting any light at all and look unnatural. Even dark eyes reflect some light.

The younger girl appears to have two right shoulders, one about four inches above the other.

The boy's left elbow appears to be missing. He's a skinny kid, but I doubt he would naturally hold his elbow so close to his body that it would be completely behind the young girl.

The area where the young girl's (lower) shoulder meets the pleating of the boy's shirt has something weird going on.

I don't know where those glasses came from, but they don't belong to the older girl. Look through the left lens of the glasses and notice how her face has a glaringly broken edge. Also, the glasses just seem to be "floating" on top of her face. Not even a single strand of hair is over the glasses, which seems unlikely. I think what you did was clip the glasses from another model and plunk them onto the older girl. Then you cut out the right lens (notice how there's no glare where the glass would normally be) to let her true face show through. But you apparently had some problems with the left lens, and it looks like the skin from the other model has been put on top of the older girl. Then to make up for it, you tried to make both eyes, especially the pupils, look the same.