I don’t think a mom prefer one sibling over the others. But the professors think the opposite.
Here is the article.
So they started a study including mothers who were between the ages of 65-75 and had at least two living adult children. They asked the mothers such questions: “Which of your children are you most likely to talk to about a personal problem?”; To which child do you feel the most emotionally close?” and “Which child are you most proud of?” etc. And then they asked similar questions to the adult children of the moms: “Which child does your mother feel the most emotionally close to? etc.
And they claimed that they can find the favorite sibling of the moms.
In general, daughters were overwhelmingly chosen over sons and lastborns were also selected more frequently than first or middle children.
7 years later they followed up their research and that time moms were between the ages of 72-82. They wanted to find out whether receiving care from a preferred child (or a non-preferred child) would affect a mother’s psychological well-being. The answer is no. However, if they received care only from their non-preferred kids, the mothers were more likely to be depressed.
It calls a scene from “This is Us” to mind. When two siblings were accusing their mother of loving their third sibling most the mother replied: “He was easy to love”.
I don’t think this favorite child thing has something to do with “love”. It is all about the bond between mom and the child and receiving the care. Sometimes it can be easier to love someone. It is totally okay for me to prefer the one who loves back over the one who doesn’t. We’re human.