Best example about this one is those 'I have only girls' or 'I get only boys'. Don't know what the percentage is for getting girl or boy, but when you get 10 boys in a row and percentage is 50% you have just beaten up statistics.(~0.097% chance to get 10 boys in a row.)

Example -> http://cs.joensuu.fi/~ppakar/seka/mtw2_006.jpg
(~0.3% chance to get 8 girls with 50%. If recall correctly it got even worse, but I haven't taken screenshot about it. This happens way too easily somehow.)

When testing this bug you shouldn't do every action in a row, but you should do a action then do something else like you do in real game and then again try that action and so on.

Skott:
Random generator affects whole game. Nearly everything you do is calculated with random generator somehow.