How Young is Too Young to Wear Thong Underwear? | Families

I was recently in a major department store shopping for clothes for a little girl.  When passing by the underwear section, I couldn't help but notice there were thong underwear for sale.  I honestly stopped walking and took a second look to make sure my eyes weren't deceiving me.  I was kind of shocked to see thong underwear being sold in the girls department for girls wearing sizes 7-14.

Am I alone in thinking that girls between 7 and 14 years old probably shouldn't be wearing thong?  I just think that's too young for thong underwear.  I know that some women wear thong for comfort or to hide underwear lines under their clothing.  I also know some women wear them strictly for sex appeal.  Either way, what age do you think is appropriate for a woman and/or a girl to start wearing thong underwear?