Olympic gymnast Nastia Liukin's thigh gap needs to be seen to be believed. The 31-year-old five-time Olympic medalist, fresh from inking a movie deal in "Little Gymnasts," has been shouting out her own inner little gymnast by thanking one of the people who passed down the gene set – her mother. Nastia, raised by two Olympic gymnasts in Russia before moving to the U.S. as a child, today took to Instagram to wish mother Anna Kotchneva a happy 51st birthday. Check it out below.