I had nothing with my first preg, no M/S, no ill feeling nothing at all... I had a girl...
I fell preg felt icky but lost that baby (do not know gender)..
With my last preg I had motion, movement, smell, senses sickness, but only spewed after meals.. Another girl....
So I think it's all different...
Both of my sisters 1 older & 1 younger were hospitalised during their preg's with morning sickness & dehydration...
My Mum was fine with baby #1, but with me she was awfully ill & couldnt feed my sister her brekky as it made her vomit, with my younger sister she ate anything & everything & was fine!!!???

So I dont think any theories are ever concrete!

I still get told now by people that ask if I have kids & were the preg's the same & I tell them they were totally opposite including the way I carried etc, they say... So you have 1 of each, I say Nope & then they always say, you've got 2 boys!? Nope 2 girls, they just smile then!!!??? So maybe I have wrecked their theories!???