Turtles and Conditional Probability

globals [ turtle-my-color my-turn]
directed-link-breed [ paths path]
breed [ turtle-starts turtle-start ]
breed [ turtle-ends turtle-end ]

to setup
  clear-all
  set-default-shape turtles "turtle"
  create-turtle-starts number [
    set turtle-my-color  15 + 10 * who
    set color turtle-my-color
    setxy 0 0
    set size turtle-size
  ]
  reset-ticks
end 

to go
  ;; if not any? turtles [ stop ]
  ask turtle-starts [
    ifelse label-on? [ set label who + 1] [ set label "" ]
    ifelse do-stamp [ stamp ] [  ]
    ifelse is-pen-down [ pen-down ] [pen-up]
    move ]
  ;;ask links [ connect-turtles ]
  tick
end 

to move  ;; turtle procedure
  set my-turn  2 * (random angle) - angle / 2
  rt random angle  ;; right turn
  ;;lt random angle  ;; left turn
  ifelse stepsize = 0
     [ setxy random-xcor random-ycor ] ;; random jump
     [fd stepsize ]   ;; forward
end