i have heard that old wives tale and from *my* personal experience it was true.

with DD1 i was laid back and nothing fazed me (even though my Dad was terminally ill at the time and passed away 2 weeks before i gave birth to her at the same hospital) and she was a dream child. DD2 i had a very stressful pregnancy and she was vile (yep it sounds harsh, but she was). severe reflux, almost non-stop crying for the first 9 months of her life. it truly was horrible and the reason why we didn't go for #3 and DH had a vasectomy when she was 11months. even now she is still my "highly strung" child. i love her more than words can express but she was hard work

eta: of course it could all just be coincidence and it is just her personality and for every story like mine there will be just as many to counteract it