In the presence of our in-laws, conflict often arises from the tiniest issue. Our mother-in-law compliments or corrects a child, and we want to scream. Our daughter-in-law declines our offer to help her prepare the dinner, and we feel rejected. Since showing our irritation or hurt is bound to make things worse, we bottle our anger or disguise our affront, and this can make us feel worse as we ruminate on the offense.
An evolutionary perspective explains our “irrationality”
A recent study  looks at very common but often misunderstood problems with in-laws from an evolutionary perspective. The new research supports my own data  on in-law conflict showing that tensions between daughter-in-law and mother-in-law are the most common, though the newer research also finds that in-law complaints (from both daughter-in-law and son-in-law ) are more likely to be directed towards the mother-in-law than the father-in-law. The researchers conclude that the underlying explanation for these problems may well be genetic. This does not mean that they have identified genes for in-law conflict. What they mean is that it is the genetic bond between parent and child that generates a disposition for parents to prioritize their own kin in the allocation of resources, such as money or care, over their in-laws. When in-laws expect what counts as “family fairness,” they are often disappointed.
This research was presented in the popular press as showing that in-law tensions are “all in the genes.” What the researchers in fact say is that “affinal” or relationships formed by marriage are likely to have a genetic component, just as they do between those who share a pot of genetic material. What interests me here is how compelling many find the genetic explanation for in-law conflict.
“It’s all in the genes” is an explanation that might be comforting. For example, we no longer have to brood over our own unreasonable or ungenerous behavior when we snap at a mother-in-law who is “only trying to help.” As a mother-in-law, we don’t have to ask, “What have I done wrong?” when our daughter-in-law seems cool or even surly. It isn’t us, it’s evolution.
Two key concepts can improve in-law relationships
Setting aside some problematic details with the evolutionary explanation in the new research — for example, the study shows that fathers get on better with their daughters-in-law than with their daughters — there is also a downside to the conclusion that “it’s in the genes.” This seems to be one of those explanations that ends the story. Why look further into the problematic relationship if there is a genetic explanation? Why hope to use such understanding to moderate conflict if it is “all in the genes?”
In my work on family dynamics, I also show that the investment parents have in a child creates complications between in-laws. The psychology of parental investment has undoubtedly emerged from the genetic imperative to put one’s children first, but this knowledge is not helpful. However, two key concepts do help with in-law conflict: love and respect. Only in understanding the power of our need for love and respect can improve in-law relationships.
Each woman, mother-in-law and daughter-in-law, wants to be the A person in her family, whose needs and values carry authority. When a woman’s mother starts telling her “what she should do” the daughter, as the wife/mother in her household, can express her irritation, challenge her mother and move on. The rhythms of mother/daughter conflict are, by this time, well oiled. If she challenges her mother-in-law, however, those rhythms jerk and break. Each is alarmed by what might happen, so each turns away from the other when dissatisfaction percolates. Perhaps, instead of direct confrontation, each complains to the man in the middle, the son and partner, who often makes things worse by defending his mother (so the wife feels undermined and betrayed); or, he defends his wife against his mother’s complaints, so his mother worries that she is losing a special closeness to her son.
Another notable absence in any genetic explanation (acknowledged by the researchers themselves) is family culture. Each family has its own set of rules that members generally follow. More often than not, the rules disappear into the background and emerge simply as measures of what is “normal” and what is “right.” It is likely that family culture has much to do with disagreements over money and care, as well as love and respect. If we are to understand in law conflict in ways that improve affinal relationships, we need to understand how people themselves respond to specific interactions between them. When we keep our focus on that, we can improve in-law relationships, even though some of the conflict may indeed arise from our selfish genes.