Not only did Guerrero become the youngest Blue Jays hitter to reach 40 homers and one of just 10 in franchise history, but he and his father are now one of just two father-son duos to hit 40 home runs, joining Prince Fielder and Cecil Fielder.
Vlad Sr. hit 42 home runs when he was 24 with the Montreal Expos and reached the 40-homer plateau once more the next season, totaling 449 in his Hall of Fame career. Vlad Jr. has a long way to go to reach that mark, but he is now third in the Majors in home runs this season behind Salvador Perez (41) and Shohei Ohtani (43).
Cecil Fielder reached the 40-homer mark twice in his career, first in 1990 when he clubbed 51, then again the next year when he hit 44. Both totals led the Majors and came during Fielder's seven-year run with the Tigers. He also hit 39 in 1996, which he split between Detroit and the Yankees. Prince Fielder reached the mark twice with the Brewers; he led the NL with 50 homers in 2007, then socked 46 in 2009.
Bobby and Barry Bonds came just short of joining the club. Barry, the all-time home run king, hit at least 40 homers in eight of his 22 seasons. His father, who amassed 332 dingers in his memorable 14-year career, came so close when he hit 39 with the Giants in 1973. He came close again in 1977 when he went deep 37 times.
Similarly, Ken Griffey Jr. hit at least 40 homers seven times in his Hall of Fame career, but his father, Ken Griffey Sr., wasn't as much of a power threat, topping out at 21 in 1986, which he split between the Yankees and Braves.