Why is my python function not generate the expected output?

I wrote a rather simple program in Python. Here is the code:

import pygame
import time
from math import *
from random import *
from pygame.locals import *




def mutateBrain(brain):
    a = 0
    for element in brain:
        brain[a][0] = element[0] + (1 * (0.5 - random()))
        brain[a][1] = element[1] + (1 * (0.5 - random()))
        a = a + 1
    return brain;


def generateFirstBrain():
    genbrain = []
    h = 0;
    while randint(0,5) != 0:
        asd = [2 * random(), 2 * random()]
        genbrain.insert(h, asd)
        h = h + 1
    return genbrain

pygame.init()
width, height = 640, 480
screen=pygame.display.set_mode((width, height))



screen.fill(pygame.Color(255,255,255))

pygame.draw.rect(screen,(255,0,0),(310,0,30,30))
movesa = generateFirstBrain()
movesb = generateFirstBrain()
movesc = generateFirstBrain()

cola = (255,255,0)
colb = (255,0,255)
colc = (0,255,255)


while 1:

    movesa = mutateBrain(movesa)
    movesb = mutateBrain(movesb)
    movesc = mutateBrain(movesc)

    step = 0
    acurrentx = 320
    acurrenty = 240

    bcurrentx = 320
    bcurrenty = 240

    ccurrentx = 320
    ccurrenty = 240

    totalsn = 0



    if (len(movesa) >= len(movesb)) and (len(movesa) >= len(movesc)):
        totalsn = len(movesa)
    elif (len(movesb) >= len(movesa)) and (len(movesb) >= len(movesc)):
        totalsn = len(movesb)
    else:
        totalsn = len(movesc)

    for g in range(totalsn):
        screen.fill(pygame.Color(255,255,255))
        pygame.draw.rect(screen,(255,0,0),(305,0,30,30))

        try:
            acurrentx = acurrentx + 1 - movesa[step][0]
            acurrenty = acurrenty + 1 - movesa[step][1]
        except IndexError:
            acurrentx = acurrentx


        try:
            bcurrentx = bcurrentx + 1 - movesb[step][0]
            bcurrenty = bcurrenty + 1 - movesb[step][1]
        except IndexError:
            bcurrentx = bcurrentx

        try:
            ccurrentx = ccurrentx + 1 - movesc[step][0]
            ccurrenty = ccurrenty + 1 - movesc[step][1]
        except IndexError:
            ccurrentx = ccurrentx

        pygame.draw.rect(screen,cola,(acurrentx,acurrenty,4,4))
        pygame.draw.rect(screen,colb,(bcurrentx,bcurrenty,4,4))
        pygame.draw.rect(screen,colc,(ccurrentx,ccurrenty,4,4))
        pygame.display.flip()

        time.sleep(0.01);
        step = step + 1

    dista = sqrt((acurrentx - 240) ** 2 + (acurrenty) ** 2)
    distb = sqrt((bcurrentx - 240) ** 2 + (bcurrenty) ** 2)
    distc = sqrt((ccurrentx - 240) ** 2 + (ccurrenty) ** 2)



    if(dista<=distb and dista<=distc):
        print("a")
        movesl = movesa
    elif(distb<=dista and distb<=distc):
        print("b")
        movesl = movesb
    else:
        print("c")
        movesl = movesc

    movesa = mutateBrain(movesl)
    movesb = mutateBrain(movesa)
    movesc = mutateBrain(movesb)


    movesa = mutateBrain(movesa)
    time.sleep(0.01)
    movesb = mutateBrain(movesb)
    time.sleep(0.01)
    movesc = mutateBrain(movesc)

while 1:
    pygame.display.flip()
    for event in pygame.event.get():
        if event.type==pygame.QUIT:
            pygame.quit() 
            exit(0) 

Here, at the end of the first while loop, movesl always gets the same value no matter how many times I run the mutateBrain function. But it changes so there should be a problem with the random. Could somene please help me with this? Thanks.