Giovanni is the son of Matteo, who is Sofia's brother. This makes Giovanni Sofia's nephew. In relation to Lucas, since Matteo is his uncle (the brother of his mother Sofia), Giovanni is Lucas's first cousin.

Gabriella is one of Sofia's sisters. Since Sofia is Lucas's mother, her sisters (including Gabriella) are his aunts. Therefore, Gabriella is Lucas's aunt, and Lucas, her nephew.

Marco is Matteo's son and not Sofia's son. Sofia has only been indicated to have one son, Lucas. As Matteo is Sofia's brother, that makes Marco her nephew, and not her son.
Lucas is Sofia's son. Sofia has one brother, Matteo, and two sisters, Isabella and Gabriella. Matteo has two sons, named Giovanni and Marco, and Gabriella has a son, named Ricardo. Describe how Sofia might be related to Giovanni and Gabriella's relation to Lucas. Additionally, elaborate on why Marco is not Sofia's son.

Provide a very brief response.