I actually think it's pretty irresponsible of your chiro to tell you that! Sorry, but I wouldn't be paying any attention. Your OB is far more qualified to advise you on that and I'm just really sorry that your chiro has given you more reason to doubt your ability to birth your baby vaginally.
As rayray said, if you do WANT a c/s, then get another dr, but if your worry is based on your chiro and your family's experience, then I'd say research some more. Find yourself some fabulous support and do some calmbirthing or grab a pink kit. If you are confident in your ability to birth, that's your best chance to do so.
If you'd like a second opinion from another OB (one who you are confident has listened to and not just rudely dismissed your concerns!) go for it. I'd say that'd be wise. But I personally wouldn't go to a different chiro for an opinion on your capability of birthing a baby! JMO.