In this note, based on archival documents, we supplement and clarify information about the father of Alexander Grothendieck, most of which is in the biography of Grothendieck, written by W. Scharlau. We managed to establish the real name, given at birth to Alexander Petrovich Shapiro and establish with certainty that he had at least three brothers. In addition, we found out the fate of A. P. Shapiro’s eldest son, David Alexandrovich, and established contact with his daughter. In the mid 90s, D.A. Shapiro dictated to her several pages of memoirs about his parents, where he told the real name of his father, grandmother, the history of acquaintance of parents and other information that he knew from the words of his mother.