We often talk about people by their "generation" in the United States—since people in this country are overwhelmingly immigrants or descended from people who immigrated in the last 400 or so years, most everybody is Nth generation for some N. On my super-paternal side (fathers all the way up, that is—I'm just inventing genealogical terms here), my grandfather's grandfather came to this country from Poland, which makes me fifth generation in that branch. (By some counting, I'm fourth-generation because it was my grandfather's father who was first, his father, the immigrant, not getting a generation number. That numbering system doesn't work for me, so I'll discard it here.) So what about on the A's? How did the current 40-man roster (plus 60-day DL) get to Oakland Athletica?

Anybody who is acquired in trade is mostly unclassifiable because trades often involve multiple players—if X is traded for Y and Z, then X's parents are both Y and Z, but if Y and Z are different generations, then how do you classify X? Half-numbers? That's dissatisfying (especially if Y is 2nd and Z is 4th—is X now 3rd?), so what I'll do is identify the major piece on the other side of the trade as the sole parent of the player in question. See Josh Donaldson below for an example: I'm counting Rich Gaudin (2nd generation) as a throw-in with Rich Harden (the major piece) in determining who Donaldson's parent is.

As you'll see, if someone was drafted with a compensation pick because of the loss of a free agent, I count that free agent as the player's parent.

First-generation players (i.e. drafted by the team or signed as a free agent)

1. Grant Balfour (FA)
2. Vinnie Catricala (cash or PTBNL)
3. Yoenis Cespedes (FA)
4. Jesse Chavez (cash)
5. Bartolo Colon (FA)
6. Coco Crisp (FA)
7. Pedro Figueroa (FA)
8. Nate Freiman (Rule 5)
9. Grant Green (draft)
10. AJ Griffin (draft)
11. Arnold Leon (FA)
12. Luke Montz (FA)
13. Brandon Moss (FA)
14. Hiro Nakajima (FA)
15. Pat Neshek (cash)
16. Hideki Okajima (FA)
17. Dan Otero (waivers)
18. Evan Scribner (waivers)
19. Dan Straily (draft)
20. Stephen Vogt (cash or PTBNL)
21. Jemile Weeks (draft)
22. Michael Ynoa (FA)

Second-generation players (i.e. acquired via a first-generation player)

1. Ryan Cook < Trevor Cahill
2. Josh Donaldson < Rich Harden
3. Sean Doolittle < Barry Zito
4. Jarrod Parker < Trevor Cahill
5. Andy Parrino < Tyson Ross
6. Josh Reddick < Andrew Bailey
7. Andrew Werner < Tyson Ross
8. Chris Young < Cliff Pennington

Third-generation players

1. Brett Anderson < Dan Haren < Mark Mulder
2. Jerry Blevins < Jason Kendall < Arthur Rhodes
3. Adam Rosales < Aaron Miles < Jeff Gray

Fourth-generation players

1. Jed Lowrie < Chris Carter < Dan Haren < Mark Mulder
2. Fernando Rodriguez < Chris Carter < Dan Haren < Mark Mulder
3. Scott Sizemore < David Purcey < Danny Farquhar < Rajai Davis
4. Seth Smith < Josh Outman < Joe Blanton < Jason Giambi
5. Eric Sogard < Scott Hairston < Sean Gallagher < Rich Harden

Fifth-generation players

1. Tom Milone < Gio Gonzalez < Nick Swisher < Johnny Damon < Ben Grieve
2. Derek Norris < Gio Gonzalez < Nick Swisher < Johnny Damon < Ben Grieve
3. Shane Peterson < Matt Holliday < Carlos Gonzalez < Dan Haren < Mark Mulder

Sixth-generation players

1. John Jaso < A.J. Cole < Gio Gonzalez < Nick Swisher < Johnny Damon < Ben Grieve
2. Michael Taylor < Brett Wallace < Matt Holliday < Carlos Gonzalez < Dan Haren < Mark Mulder