Family members 

Mother = Madre

Father = Padre

Brother = Hermano

Sister = Hermana

Uncle = Tío

Auntie = Tia

Grandfather = Abuelo

Grandmother = Abuela

Male cousin = Primo

Female cousin = Prima

Nephew = Sobrino

Niece = Sobrina

Stepbrother = Hermanastro

Stepsister = Hermanastra

Stepfather = Padrastro

Stepmother = Madrastra

Twins = Gemelos