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NovemberMum 
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Joined: 16 March 2007
Location: Hamilton
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 Topic: not sure where she learnt that from
Posted: 18 September 2007 at 1:54pm |
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was talking to my sister a little while back and we were talking about babies before they were born and she said that all unborn babies start out as females..
ok now when I did basic science in 3rd or 4th form we were taught that the females have X eggs and the males have X and Y sperm, and depending on which sperm fertilizes the eggs determines if the baby will be male or female.
however I have recently discovered the the sexual organs don't develop until about 14 weeks?
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daikini
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Posted: 18 September 2007 at 2:00pm |
Ummm... I'll ask my husband when he gets home - he's a high school science teacher, and he majored in Mammalian Physiology (which is a flash way of saying he can teach biology  )
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Becca, mum of 2 girls & 3 boys
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Bizzy
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Posted: 18 September 2007 at 2:04pm |
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you are right, the sexual orgnas dont develop till later but the sex has alredy been decided...
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caliandjack
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Posted: 18 September 2007 at 2:07pm |
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Yep it is true, its not until testorterone kicks in that the male sex organs develop.
Studys have shown girls that are exposed to more testosterone in the womb are more likely to pursue male orientated interests and careers.
Genetically they are XY or XX from conception.
Edited by fleury
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busymum
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Posted: 18 September 2007 at 4:35pm |
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Most people think of babies as "gender neutral", or girls, until around 12 weeks when the sexual organs begin. I'm glad to see that they actually ARE a particular sex from the start, I always thought that must be the case.
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LittleBug
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Posted: 19 September 2007 at 6:45am |
They are definitely boy or girl from the start, but as someone else said, they are "gender neutral" with regards to external genitalia until around 12 weeks when they start differentiating into male or female based on the presence of testosterone or not (which is dependent on whether bubs has XX or XY genes of course).
U can trust me, too... my major at uni is human reproduction and development 
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Chloe (4 years) and Oliver (3 years).
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LittleBug
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Posted: 19 September 2007 at 6:48am |
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Oh, I forgot to add... if there is no testosterone present, female organs will develop which is sort of the "default" pathway I guess. That might be why some people think that all babies start out as females, even though its not true, genetically.
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Chloe (4 years) and Oliver (3 years).
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DJ
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Posted: 19 September 2007 at 7:04pm |
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I think there is a theory that featured in an old documentary called "the fight to be male". The evidence suggested that the natural inclination of the foetal material is to be female at conception - that might be where that idea came from. I don't know if the theory is still valid...
Also don't know how that little gem remained in my brain considering what else I can't remember at the moment...
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emz
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Posted: 19 September 2007 at 7:38pm |
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If you see pictures of a foetus at 10 weeks, there are lumps that will either drop and develop into testicles, or rise and form ovaries. There's also a hole type thing that either pulls out and becomes the penis with urinary gland, or the clitoris with the urinary gland there.
And not everyone is XX or XY. About 4-5% of people have 'mutated' genes which means you could be XXY, XYY or other combinations. (Hence where really testosterone-filled males come from - XYY's have too much Y in my view!)
I only learnt this a few weeks ago, I've just done an intensive course in Sexuality Education which really opened my eyes!
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not sure where she learnt that from
