There are numerous mother-in-law jokes and step-mother jokes. Remember the wicked step-mother in Hansel and Gretel?
I over-heard recently: At a family re-union the step daughter (who has two children) said to her step mother over lunch hearing that a half-brother and wife were soon to have a child: “Oh, now you can finally be a grandmother!”
That comment, certainly insensitive, probably sums up how the step-daughter views her step-mother. Dad is Dad and she comes to see her father. She brings him a card for his birthday. But she does not view her step-mother as a grandmother figure for her children. Overtures, conversation, gifts and contact may occur. But the step-daughter only thinks of her biological mother as the one and only grandmother.
And why those feelings? I know the family fairly well. What the step-mother says is that many, many years ago stories were taught to that step-daughter Not true stories. Just stories. And those stories get passed on through the generaltions. Through stories passed down from biological mother to daughter those children are taught who is kin and who is not.
Maybe that’s something that Christian churches and other faiths can offer people: a way to see “family” much more broadly. Family is more than blood ties.