Imagine a species that evolved almost identical to our own, except for one difference. A child's sex is not decided by the presence of a Y chromosome, and all embryos have the potential to evolve into either sex. The mother can decide the sex of the child she carries through regulation of hormones released during early development, which she has at least partially-conscious control over.
I'm wondering rather we would have the same sex distribution as we have now? Keep in mind that in the wild a sex distribution of 50/50 would be expected due to fisher's principle. However, technology tends to modify the way humans view the world. I suspect primitives humans would have the same 1:1 ratio, but would modern humans with modern technology and culture still maintain this ratio? what factors may cause a change in this ratio.
P.S. Keep in mind the evolutionary psychology. They would have evolved to have an instinctual understanding of fisher's principle which would likely limit extremes shifts either way.