Does the oboe have siblings?

It does. They are;

the Piccolo Oboe (Oboe Musette)

the Oboe (including various versions of today's Oboe, including different Baroque, Classical, and Romantic models)

the Oboe d'amore

the Oboe da Caccia also known as 'taille de hautbois'

the English Horn (Cor Anglais or Cor Angle)

the Bass (or baritone) Oboe

the Contra-Bass Oboe

the Heckelphone