I'd be interested in seeing any research you may have seen that supports your position. Anecdotally, that hasn't been my experience (in those around me, obviously)
However, I see that there is nothing in the article specifically about primary caregiver being female. To summarize, it is better to have one primary caregiver who has established a strong attachment with child. Traditionally it has been a female role, and I do believe women are better suited for it.
I don't see anything in that article to suggest 1 primary caregiver is best. The sense I got was that children got a benefit from having a strong attachment, but no arguement or experiment to test for weather 1 strong attachment is better than 2, possibly weaker, attachments.
Also, I am always suspisous of 2nd hand science reports, especially when they do not provide a direct link to the original paper(s). If anyone does track down some research papers on the subject, please post it here.
Sort of ditto gizmo686; the article cited confounds primary caregiver and mother, and I would be surprised if the authors of the source articles had the kind of data that would disambiguate the two. Which women are better than which other caregivers? The idea that every women/mother is automatically better suited as primary caregiver is a old stereotype that continues to do harm.
