I have a friend who has been sleeping with her daughter (or vice verse) since birth, and her daughter will soon be 12. This friend was married until one year ago, when she divorced her husband based on emotional and verbal abuse, and numerous affairs. She has been visiting me for the last two months, and I purposefully gave them each their own room, with lots of hints, but to no avail. I feel it is very unhealthy for them both. Should I leave it alone?
First of all while I appreciate your concern it really is none of your business.
As for the why, it isn't unhealthy unless the 12 year old wants to pull away and mom won't let her. They maybe emotionally soothing each other of their losses. Children who co-sleep often climb back into bed with their parents even into their teens. I know of a young woman who when she is home insists on climbing into bed with mom and dad just for a few moments of remembrance.
As long as it is about the daughter wanting to be near her mom there is no harm. Other countries co-sleep for a lot longer than we do in the US. We are uncomfortable with some behaviors because it doesn't fit into our own world of what is okay. However, this doesn't mean we should impose all of our own "okayness" upon others.
Your friend is fortunate to have a friend who obviously cares about her and who she can stay with and you will do well to let things be and just enjoy your company.
M Kay Keller