The Pauline Epistles
The earliest Christian writings, the Pauline epistles, do not contain any mention of a virgin birth and assume Jesus’s full humanity, Mark, dating from around AD 70, has no birth story and states that Jesus’s mother had no belief in her son as if she had forgotten the angel’s visit.[26] Matthew and Luke are late and anonymous compositions dating from the period AD 80–100, and it is almost certain that neither was the work of an eyewitness.[27][28][29] This raises the question of where the authors of Matthew and Luke found their stories. Both used Mark as their basic source, but the virgin birth is not found there, nor, in view of the many inconsistencies between them, did one of them derive it from the other or share a common source.[2] Raymond E. Brown suggested in 1973 that Joseph was the source of Matthew’s account and Mary of Luke’s, but modern scholars consider this “highly unlikely”, given that the stories emerged so late.[30] It follows that the two narratives were created by the two writers, drawing on ideas in circulation in some Christian circles perhaps by around AD 65.[31]
Wiki
https://www.britannica.com/topic/biblical-literature/The-Pauline-Letters