If the child feels ugly a makeover can do the trick. I mean a makeover without surgery, a dentist and all those tricks that won't make a person more attractive but closer to scary (keep Michael Jackson in mind).
Make up can be a great help. It's used since centuries although today it's mainly about chemicals.
Not everyone looks better with makeup and some skills are needed (photoshop is easier or a program photographers use they can make you look better, slimmer and even add make up on).
I asked the model in our family for some tips. She offered to send a box. I'm still waiting for it so we decided to try out something ourselves. Weekends are great for trying out.
See 
Prompt used: make up