Since his brother, Yasumori, two years his junior, took the name of "Kuro," whose name was traditionally used by the heir and son of the Adachi Clan, from the beginning, Yorikage seemed to be an illegitimate child.
頼景の2歳年下の弟泰盛が、当初から安達氏の嫡男が継承する「九郎」を名乗っている事から、頼景は庶子であったと思われる。