Martina and Javier are siblings. Martina is married to Liam and they have a son named Hugo. Javier has two children, Sofia and Carlos, with his wife Lucia. What is the relation of Liam to Sofia and Carlos? What is Hugo's relation to Javier and Lucia? What is the relation between Hugo and Sofia? Respond very briefly.
Liam, being Martina's husband, is the uncle of Sofia and Carlos because they are Martina's niece and nephew through her brother Javier.

Hugo, being Martina and Liam's son, is the nephew of Javier because Javier is Martina's brother. Hugo is also the nephew of Lucia by marriage since Lucia is Javier's wife and the mother of Hugo's cousins, Sofia and Carlos.

Hugo and Sofia are first cousins because their respective parents, Martina and Javier, are siblings. Hugo and Carlos also share this first cousin relationship for the same reason.