Lianna Grethel was born in Hartford, Connecticut but soon moved to Cali, Colombia. It comes as no surprise that Grethel entered the entertainment world; her mother, Consuelo Portuondo, was one of the most successful Colombian model of her time. Grethel's grandfather, Enrique Portuondo, was a well-known director and television host in Habana, Cuba. Throughout her childhood, Grethel's participated in every theatrical and musical production she came across. But it wasn't until she was 16 years old that she had her first national television ad campaign. Throughout her teenage years she continued in runway shows, photography modeling and television.