Which pedigree symbol is used to represent a female carrier of a recessive X-linked trait?

In humans, the ability to bend the thumb back beyond vertical is called hitchhiker's thumb and is dominant to the inability to do so (OMIM 274200). Also, the presence of attached earlobes is recessive to unattached earlobes (OMIM 128900).

Check your own phenotype and those of several friends or classmates.