I think there are so many other variables that have more of an influence on the progress of labour than heredity. Such as your age versus your mother's age when you first give birth. My mum was 25, I was 30. Women of our mother's generation were often made to labour on a bed; women these days are more free to be vertical and active.

These are the factors I think affect length of labour more than heredity:
* gravity
* freedom of movement
* privacy and a supportive, respectful atmosphere
* the position of the baby - anterior is optimal
* calmness & confidence of the mother, as opposed to fear, tension, stress (e.g. if her social situation is stressful)
* general health of the mother, nutrition, fitness, other health issues or complications
* attitude of caregivers and supporters to birth and towards the birthing woman
* warmth
* dimmed lights (bright lights & cold can trigger stress hormones that inhibit labour progress)
* minimal interruptions and monitoring
* good sounds - music of choice and gentle voices, not thoughtless chatter or scary comments

I do think that it's worth checking out your "birth heritage" with mothers, grandmothers, aunties, cousins etc. If they could do it, it's encouraging for you - that you can walk in their steps too! But I think when it comes to the actual length of labour, there's too many other personal factors that are likely to over-ride any familial pattern.

That was the case with me, anyway. My mum had 4 babies in hospital and I had 3 at home, so our births were quite different. One thing was similar tho - she did it. And I did it. But we think mine were less traumatic because I had the luxury of giving birth in a nicer, more supportive environment. I won the record for the longest labour in three generations in my family with baby #1 (it was only 24 hours!?) but then I blasted the records again by having the quickest labour next time round: 3 hours.