More than any other professional sport, NBA basketball is a family business. For evidence, look no further than the reigning champion Golden State Warriors.

The father of two-time MVP Stephen Curry, Dell, played in the NBA for 16 seasons as an expert outside shooter. His brother, Seth, plays for the Sacramento Kings. Curry’s backcourt mate Klay Thompson is the son of Mychal Thompson, a former No. 1 draft pick of the Trail Blazers and two-time NBA champion. Warriors guard Brandon Rush has two brothers—JaRon and Kareem—who...