Is it true some couples can only have either all male or all female DC?

[maybemumm]

My friend is pregnant and her DP has two daughters from another relationship. She said the baby would be a girl because her DP only makes girls, and it’s just confirmed to be a girl.

Is it true that some couples (men, in particular, as I know it’s men who influence it) can only biologically make either female or male offspring?

My DH’s family is the same. All boys as far as he’s traced. I had a son & he has all boys.
As to large families my GM on my DM’s side was the youngest of seventeen children, all boys except for one other girl. Sadly all her brothers except for two who were too young to fight were killed in the First World War.

If a man has a mutation on one of his sex chromosomes that means a foetus cannot develop, then theoretically if the mutation is on the X chromosome, he wouldn’t be able to father girls, and vice versa.

same with a woman, if she has a mutation say on her X chromosome that means she needs another x to provide the healthy gene, she’s only be able to carry girls.

i doubt the research has been done as if you’re having healthy babies it won’t be considered a priority.

I believe studies show that the more boys born to parents the higher the probability of the next child being a boy, but not so for girls. It’s a small difference though. http://www.ingender.com/gender-info/odds-of-having-another-boy-or-girl.aspx

Think about it, if you toss a coin three times, you could easily get the same result each time. That's exactly what this is. If you tossed a coin twice and got "heads", and then tossed it again and got "heads" again, would you say "Ah yes, that's because I can only ever get "heads""?

I read that some men produce more X sperm and some produce more Y sperm and some produce an even number.

I do see some women with kids all the same sex but I have also seen in my age group, one of each.

I have one of each.

This.

Some men do produce more of one sex sperm.

https://www.sciencedaily.com/releases/2008/12/081211121835.htm

I did hear that men with more sisters are more likely to father daughters and men with more brothers more likely to father sons. But obviously that doesn't mean incapable of fathering the other and I don't think it was a big probability difference.

My grandfather only had brothers and then had 5 daughters himself. My DH has 3 sisters, no brothers, and we have 1 of each. It's probably at the population level that you'd see the trend, doesn't mean too much for individual families.

I remember an old neighbour on six boys and desperately wanting a girl, all the conversations seems to be around the fact that either the husband clearly couldn’t make girls or that she just couldn’t carry girls and god knows she was trying all
the voodoo and whatnot.

One section of family seems to have a few generations of only boys.

Not sure about the comment if other half has brothers or sisters. My other half has only sisters yet we had 2 boys first then twin girls lol

I think that it's usually just probability and given how many families there are, some will have an unusual pattern.

One of my cousins has seven girls (two different fathers).
Someone else I knew had six boys before having boy/girl twins. She really wanted a daughter!

It's very much an old wives' tale. My parents had 3 sons. My SIL was one of 12 kids - 8 girls, 4 boys

There's a short podcast about this just released, by Hannah Fry. Basically if you have a lot of sex, as returning soldiers were likely to do, you conceive earlier in your cycle. And that means you have more chance of getting a boy

Just look at people with loads of kids to test it. Off the top of my head… Tyson Fury! 😁 I think they’re a rough 50:50 ish split actually.

I was surprised I had a girl for this reason given she was conceived in the immediate honeymoon period. 🙈

I listened to Hannah Fry's podcast but wasn't at all convinced. You conceive at the time you ovulate and ovulation will not move earlier or later depending on how much sex you have. I think the returning soldier effect could be down to those people having sex every day and therefore hitting ovulation day which perhaps more often results in a boy - while those who have more infrequent sex are less likely to have sex on the day of ovulation itself.

There is a genetic condition in my friends family that only effects girls and most don’t go to full term.

I have 5 boys and 2 miscarriages. It's possible that some couples can only have babies of one sex but you would need to find a lot of couples willing to have 20+ children to prove that theory!

I know someone with 7 girls….they kept trying 1 more time for a boy. My sister has all boys, 4 of them.

Weather that just the way the coin fail or they can only carry one sex who knows

But if a man has a mutation on either his X or Y chromosome that is incompatible with life then he couldn't be alive.

Each man only has one of each. So if it was a dominant mutation (i.e you only need a single copy for a problem) then it would also have prevented him from living.

(And if the mutation developed as an adult it wouldn't impact all sperm.)

Your uterus knew something!

The nearest thing to adequate data on this is the New York longitudinal survey.

It found that if a couple had 3 boys already, then there was a higher than expected rate of 4th boys - should be just over 6% (on straight 50/50) but was 9% (so 50% higher than it should have been.

If it was a run of girls, or fewer than 3 boys, then it remained 50/50

And interestingly the more older brothers a boy has the higher the likelyhood he’ll be gay is. There’s a biological reason for it.

it wouldnt surprise me if there is a biological mechanism at play that would increase the ratio of sperm being either predominantly X or Y.

does testosterone levels play a role?
health? Diet?
presence of younger offspring influence?

it would be an interesting study to test regularly the ratio of their sperm ans see if hormones, diet or family changes impact it.

No. Although you are more likely to have a boy if you are pregnant earlier in your cycle, its negligible in one person. Generally the probability is 49/51. Just coincidence really.

https://www.sciencedaily.com/releases/2008/12/081211121835.htm

Thus study concludes that some men are genetically more likely to produce one sex over another.