From experience, do genetics determine how far into your pregnancy you are when you go into labour?

[LillianFullStop]

I ask because both my mum and my sister went into labour at 38w for all their kids.

I'm trying to work out when to start my maternity leave and if I'm anything like my mum and sis then I'd better stop before 38w!

I've no idea!I'd imagine you'll get a mixed bag of responses.
And as for the birth....My Mum had 3 straightforward natural births and I had 2 EMCS.

My Mum went to full term with my brother and induced a week early with me, I went to 40+5 rocking a weak cervix and a problematic pregnancy, neither of which my Mum had.

Both my mum and my sister went over due with all their children. My ds was 1 day early.

Mum had be at 36 weeks. I had mine all at over 40 weeks.

My mum had 3 of us bang on due date, one was one week late. My sister had 4, all between 2 and 3 weeks early. Mine were 6 and 17 days overdue. So no, no pattern here!

My two sisters were born a week early. Their children (3) have all been a week or two early. i was born a week late. My son arrived two weeks late.

Read into that what you will.

From my experience no, my grandma had long painful labours with 4DC, my DM has had 6 DC 3 short "easy" labours 3 long labours 4 over due, 1 2 weeks early and 1 due date, my DD was born at 41 weeks really quick and "easy" labour.

Nope. Mum was induced with me at 42 weeks and MIL went into labour at 41 weeks, with me dd1 was 37 weeks and dd2 32 weeks.

Doesn't seem to have had any influence here.

My mom had all of us at around 36 weeks. My sister went overdue 10 days with all of her children and I've had one at 39 weeks and one at 32 weeks.

My mum was induced with both me and my sibling due to high blood pressure. I was late.

Mine were born at:
39 - ELCS
40 - (on due date) spontaneous vbac
41+ 3 - spontaneous vbac
38 - spontaneous vbac

So I don't think genetics play an particular role

Apparently it's meant to but from both sides. My mum went around 39 weeks with both. I will be 41 weeks tomorrow my mil was 40+10 with both of hers.

I'm not even consistent with myself: dc1 37+4 and dc2 39+5 - despite all the 'first babies are usually late' and 'second babies usually come earlier than your first'!

My Mum tended to be late with her 4 as far as I know. Needed inducing with me (3) ELCS with no 4.
My dd1 was born SVD at 37 weeks, dd2 ELCS at 42 weeks. No pattern for me!

My Mum had me at 41+6 basically went into labour just as they were going to induce her, and my sister at 40+6. I had my DD at 39+4 and am currently 35+4 and waiting to see when this one arrives.... So I don't seem to have followed in my Mums footsteps yet

My first was born at 42 weeks, my second at 38 weeks, and I am currently 40 weeks with number 3.

I have spent countless hours in the past month looking for any variable that predicts the onset of spontaneous labour. There are none. It is unexplained.

It is psychological torture.

My mum was induced with me at 38+3 due to PE, she had my sister 10 days over and was induced.

My children have gone
Ds1- 42 weeks induced
Ds2- 40 spontaneous
Ds3- 38 weeks spontaneous
Ds4- 34 weeks spontaneous
Dd1- 31 weeks spontaneous (although ended in emcs at 8cm)

Not sure if mum would have been similar had she had more but first two of mine compared to mums were not the same.

My gran, mum, great aunt and sister so all close female relatives went into labour before the due date that's 11 children I was induced at 41+1 with ds. My thinking is genetics may play a part however labour is to unpredictable to be sure of anything ever.

OP, please don't base your real life decisions on the anecdotal evidence you are getting on here. Ask your MW/Doctor if there's ever been a scientific study demonstrating a hereditary component to length of pregnancy. I've never heard of it but I'm not a midwife/doctor/scientist.