I've worked full time since my son was 7.5 months. I agonised a bit before I went back to work, after I encountered some of the "nurseries are awful for boys" literature.
I am a bit of a feminist; I earn a lot more than my husband and we agreed before we married that if we managed to have kid/s I would go on working and he would do childcare. However, he would be bored at home full time, as quite possibly I would be, so we have agreed to put our son in half time nursery, though for relatively short days.
I think temperament comes into it a lot, probably more than the sex of the child. Our little boy is extremely sociable, which has been commented upon by a large number of acquaintances in the village where we live. We go to church and he zooms around, made eye contact with adults from a very young age, recognised people outside the family from a very young age, smiles very readily, approaches other small children and tries to greet them. When I have walked through the church with him, he has been observed to smile, wave and reach out to each person he passes over my shoulder.
At nursery he has been noted to settle in very quickly, to have been quick to start to share toys (another child looking with him at the starter book he is interested in) and he seems to respond very positively to his keyworker.
It has been commented that he has been seen playing peek-a-boo, gently, with the younger babies.
This is a child aged 12 months.
I do not think he is either more aggressive or sad and compliant. Neither do I think he is erm fermenting such qualities for future life.
In a different situation, I might have considered being a SAHM. It has its appeal, and I enjoyed the 8 months I spent at home more than I thought I would!
However, my experience suggests that being at (a rather good and not-for-profit) nursery part-time is a quite reasonable option for a very sociable little boy, even under 12 months.
I would add that all this treat-boys-differently stuff comes over as just a new variant on the women's-place-is-in-the-home jag. It used to be "Women can't do work/study/professions as well as men". Now, it's
"Women are doing better at work/study/professions.
So men/boys are doing worse.
So of course it's the fault of their mothers who are selfishly putting their careers above the needs of their sons, which are greater than those of their daughters, which is of course why boys are doing so badly".
Huh huh and treble huh.
Oh and I won't say what I do but I - have to go baby crying