Another interesting thread might be the relatives of athletes from other sports who played pro or college tennis. For example, former Major League baseball pitcher Bill Gullickson is the father of Carly and Chelsea. And another ex-pitcher (Phil Bradley) is Megan's Dad.
Alexandra Kiick, Top 400 WTA and Top 20 Junior, is the daughter of Jim Kiick (http://en.wikipedia.org/wiki/Jim_Kiick
) who is a famous ex-footballer who played for the Miami Dolphins in the sixties.
Coco Vandeweghe is the niece of Kiki Vandeweghe (http://en.wikipedia.org/wiki/Kiki_Vandeweghe
) who is a former professional basketball player and basketball coach. Her grandfather was also a professional basketball player. Also, Coco's grandmother (i.e. Kiki's Mum) won Miss America in 1952.
So Coco certainly has an interesting family background