NL$100, KK postflop

[wtfsvi]

UTG is 23/8/1.2 after about 500 hands. He does not bet often, especially not on the flop. Effective stacks $180. Fold the river? Fold the turn? Raise somewhere?

edited to add: He does not seem to play loose postflop.

Full Tilt Poker
No Limit Holdem Ring game
Blinds: $0.50/$1
6 players
Converter

Pre-flop: (6 players) Hero is CO with K[img]/images/graemlins/heart.gif[/img] K[img]/images/graemlins/club.gif[/img]
<font color="#cc0000">UTG raises to $4</font>, UTG+1 folds, <font color="#cc0000">Hero raises to $12</font>, 3 folds, UTG calls.

Flop: T[img]/images/graemlins/spade.gif[/img] 6[img]/images/graemlins/diamond.gif[/img] J[img]/images/graemlins/diamond.gif[/img] ($25.5, 2 players)
<font color="#cc0000">UTG bets $5</font>, Hero calls.

Turn: 8[img]/images/graemlins/spade.gif[/img] ($35.5, 2 players)
<font color="#cc0000">UTG bets $25</font>, Hero calls.

River: 6[img]/images/graemlins/club.gif[/img] ($85.5, 2 players)
<font color="#cc0000">UTG bets $70</font>, Hero..?