Yes, you are.[1]
"Domestic workers are entitled to the minimum wage, with the exception of babysitters under the age of 18 and the employer’s parent, spouse, or child."
Not nephews, cousins, and other more distant relatives.
This is California. Federal law has the "McDonald's Exception", enacted in 1996. [2] "A special minimum wage of $4.25 per hour applies to employees under the age of 20 during their first 90 consecutive calendar days of employment with an employer."
[1] https://www.dir.ca.gov/dlse/DomesticWorkerBillOfRights-FAQ.h...
[2] https://webapps.dol.gov/elaws/faq/esa/flsa/003.htm