Though many psychologists and child care experts advise against parents letting their children know who their "favorite" is, even if they have one, new research from Purdue University suggests that favoritism can have practicable applications in the long-term, Phys.org reports.

"Favoritism matters because it affects adult sibling relationships and caregiving patterns and outcomes for mothers, and now we know that who a mother favors is not likely to change," Jill Suitor, a professor of sociology who has been studying older parent relationships with adult children for nearly 30 years, told Phys.org.

"Knowing that favoritism, particularly regarding caregiving, is relatively stable will be helpful for practitioners when designing arrangements that are going to work best for moms."

About three-quarters of mothers involved in the study admitted to having one child whom they would choose as their preferred caregiver in old age, and for these mothers, this child did not change over the course of seven years.

Favorite children tend to mirror their parents in their beliefs, values and practices, as according to Megan Gilligan, an assistant professor in human development and family studies at Iowa State University and former Purdue graduate student who collaborated on the research, mothers like "the perception of similarity between herself and her child."

The new research, publishedin the Journal of Marriage and Family, are based on the Within-Family Differences Study in which data was "collected seven years apart from the same 406 mothers," aged 65-75.

Researchers found that along with similar beliefs and values, gender similarity also contributed to favoritism. Previous research has demonstrated that children tend to have the strongest bond with their same-sex parent, and a mother-daughter relationship is among one of the most potentially close and loving.

Data from the study suggested that a child's adult financial status, marital status, consistent employment and lawful behavior all mattered less to their parents than sharing similar values when it came to favoritism. It was difficult for the researchers, however, to determine what made certain children fall out of their parent's favor over the years.

"One of the few predictors of changes was when children stopped engaging in deviant behaviors, such as substance abuse, during the seven years, and then their mothers were more likely to choose them as the children to whom they were most emotionally close," Gilligan said.

However, other studies have demonstrated that playing favorites may create rivalry and resentment between children and their parents.