Since IMDB and Wikipedia are both based on user contribution and there's a good chance that they're just getting mutually copied, I would also tend to believe more "serious" sources of information.
Having to choose, I'll go with Britannica Online over IMDB and Wikipedia any time. I therefore officially decreet that on this web site Charlton Heston was born on October 4, 1924.
May he rest in peace.
May the NRA die with him and rest in pieces.