Do women retain DNA from every man they have ever slept with? No. [But this study] found male cells in 37 out of 59 women’s brains studied (63%).

Where did the cells come from? The most likely explanation is pregnancy. During implantation, embryonic cells are programmed to divide extremely fast and invade the mother’s bloodstream. Sometimes, they can establish populations in other parts of her body that survive for the rest of her life.

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There are also two other plausible sources for these cells: (1) cells from an older brother that had been retained in the woman’s mother were incorporated by the woman when she was growing in the womb or (2) cells from a male twin that was absorbed before birth.

It’s remotely possible that women might sometimes retain some non-sperm cells from male partners, since that’s never been studied and biology is weird. But there’s currently no reason to think it’s true, and many reasons to think it’s not.

The GLP aggregated and excerpted this blog/article to reflect the diversity of news, opinion, and analysis. Read full, original post: Male DNA Is Often Found In Women’s Brains. Where Does It Come From?