As adults, siblings often joke about which child was favored, but this may reflect lingering feelings of favoritism from childhood. A study found that nearly 85% of adults believed their mother had a favorite child. This perception of favoritism can persist into adulthood, with many still feeling upset about unequal treatment they experienced growing up.
https://theconversation.com/when-parents-play-favourites-what-happens-to-the-kids-110019
