Like father like son
According to this LA Times article:
The Dodgers received confirmation from the Elias Sports Bureau that the lineup they fielded in a 13-3 loss to the Colorado Rockies on Friday made history.
That lineup was the first to feature an infield consisting of four sons of four former major leaguers: first baseman Scott Van Slyke, second baseman Jerry Hairston Jr., third baseman Ivan De Jesus Jr.and shortstop Dee Gordon.
Including center fielder Tony Gwynn Jr., the Dodgers had five sons of former major leaguers, which was also the most ever in the majors.
This reminds me of reading in a book somewhere (outleirs? moneyball? freakonomics?) that the best predictor of a person making it into US MLB is if his dad also was in US MLB.