***** Hand History for Game 1111111111 ***** (Boss)
€100.00 EUR PL Omaha - Monday, May 12, 10:08:17 ET 2014
Table Georg 1 (Real Money)
Seat 4 is the button
Seat 1: Hero ( €161.32 EUR ) - VPIP: 49, PFR: 39, 3B: 6
Seat 2: Player2 ( €88.50 EUR ) - VPIP: 53, PFR: 30, 3B: 7, AF: 3,0, Hands: 43
Seat 3: Player3 ( €84.99 EUR ) - VPIP: 45, PFR: 17, 3B: 0, AF: 9,0, Hands: 47
Seat 4: Player4 ( €61.57 EUR ) - VPIP: 64, PFR: 27, 3B: 9, AF: 0,9, Hands: 173
Seat 5: Player5 ( €99.00 EUR ) - VPIP: 35, PFR: 22, 3B: 0, AF: 1,0, Hands: 23
Hero posts big blind [€1.00 EUR].
Player5 posts small blind [€0.50 EUR].
** Dealing down cards **
Dealt to Hero [  Kh As Ks Ac ]
Player2 raises [€2.25 EUR]
Player3 calls [€2.25 EUR]
Player4 calls [€2.25 EUR]
Player5 calls [€1.75 EUR]
Hero raises [€12.50 EUR]
Player2 calls [€11.25 EUR]
Player3 calls [€11.25 EUR]
Player4 calls [€11.25 EUR]
Player5 calls [€11.25 EUR]
** Dealing Flop ** [ 6h, 3s, 4c ]
Player5 checks
Hero checks
Player2 checks
Player3 checks
Player4 checks
** Dealing Turn ** [ Jc ]
Player5 checks
Hero checks
Player2 checks
Player3 bets [€21.00 EUR]
Player4 folds
Player5 calls [€21.00 EUR]
Hero folds
Player2 folds

http://www.pokerhand.org/?6672229

my problem is, I don`t think they would call without a set or a straight there but I am pretty new to plo so I don`t know what they could have here usually.

Any Ideas on how you would play the hand?