Here's a guide of some of their connections. (My first honest reaction: it does seem fairly incestuous. And then I'm not even getting into.. well, let's say more diversity would be a great thing here. All of the people mentioned here belong to one particular subgroup in the US. It just feels odd to me. Diversity hasn't reached these levels yet, I guess.)
Anne Wojcicki: CEO of 23andMe. Former part-time partner of Y Combinator, back then along with Ben Silbermann, co-founder and CEO of Pinterest; and Joe Gebbia, co-founder and chief product officer of Airbnb: https://www.bizjournals.com/sanjose/blog/techflash/2015/09/y...
Sergey Brin: co-founder of Google and formerly married to Anne.
Susan Wojcicki: Anne's sister, and CEO of Youtube, owned by Google.
Sam Altman: President of Y Combinator